North Korea has announced it will suspend its nuclear tests and uranium enrichment programme in return for US food aid, in a breakthrough less than three months after the death of leader Kim Jong-Il.

Following talks with the United States last week, the regime led by Kim's young and untested son Kim Jong-Un late Wednesday promised also to suspend long-range missile tests and allow the return of UN nuclear inspectors.

"Today's announcement represents a modest first step in the right direction," US Secretary of State Hillary Clinton told a Senate committee in Washington.

"We of course will be watching closely and judging North Korea's new leaders by their actions."

The talks in Beijing last week were the first between the two sides since Kim Jong-Un, who is in his late 20s, took power in late December.

US analysts expressed cautious hope that the deal might portend a more conciliatory posture from Pyongyang, which has built up a costly nuclear programme despite suffering from dire food shortages and grinding poverty.

But Republican critics in Washington warned that North Korea had spent years deceiving the West, and accused the US administration of reneging on repeated promises not to link humanitarian assistance to the nuclear issue.

The United States said it would provide 240,000 tonnes of "nutritional assistance". A US official said Washington rejected a request for rice and grains and instead would provide vegetable oil, pulses and ready-to-eat meals designed for young children and pregnant women.

"These are people whom the regime either cannot or has chosen not to feed," a senior official said in Washington on condition of anonymity.

The North said it would allow the International Atomic Energy Agency (IAEA) to return to monitor the moratorium on uranium enrichment, which is one way of developing nuclear weapons.

In Vienna, IAEA chief Yukiya Amano welcomed the announcement as "an important step forward" and said the agency's inspectors were ready to return.

The deal was also welcomed by Foreign Minister Koichiro Gemba in Japan, one of six countries in talks on Pyongyang's nuclear weapons that also include China, the two Koreas, Russia and the United States.

The Beijing discussions were aimed at persuading the North to return to the six-nation talks after it abandoned them in April 2009. It staged its second atomic weapons test a month later, following the first in 2006.

North Korea in November 2010 publicly disclosed the uranium enrichment programme, which could give it a second way to make atomic weapons. Its longstanding plutonium programme is believed to have produced enough material for six to eight weapons.

The North said the US side offered to discuss the lifting of sanctions and provision of light-water reactors to generate electricity, once the six-party talks resume.

In a statement, State Department spokeswoman Victoria Nuland said US sanctions "are not targeted against the livelihood" of the North Korean people.

Washington "reaffirms that it does not have hostile intent" towards the North and is prepared to take steps to improve the relationship, she said.

The United States and North Korea reaffirmed their commitment to a September 2005 six-nation deal. This envisaged the North scrapping its nuclear programmes in return for major diplomatic and economic benefits and for a peace treaty formally ending the 1950-53 Korean War.

There were widespread reports in December that the two sides were close to such a deal, but the sudden death of Kim Jong-Il threw the process into uncertainty.

The new leadership headed by Jong-Un has taken a generally tough tone with the United States and South Korea, blasting their ongoing joint military exercises as a rehearsal for war.

The US statement did not directly address tensions with US-allied South Korea. The United States has previously demanded that the North repair ties with the South before any progress between Washington and Pyongyang.

Nuland's statement said the United States "still has profound concerns regarding North Korea's behaviour" but that the agreement reflects "important, if limited, progress in addressing some of these".

Key developments in N. Korea nuclear standoff
Seoul (AFP) March 1, 2012 - North Korea has announced it will suspend nuclear and missile tests and its uranium enrichment programme as part of a deal that includes US food aid.

Here are key dates since the latest nuclear standoff erupted:

2002

- October: The US says North Korea is running a secret highly enriched uranium programme in violation of a 1994 denuclearisation accord -- a charge it denies. Oil shipments under the 1994 pact are suspended.

- December: The North unseals its plutonium-producing Yongbyon reactor for the first time since 1994 and expels inspectors from the International Atomic Energy Agency (IAEA).

2003

- January 10: North Korea says it will quit the nuclear Non-Proliferation Treaty.

- August 27-29: First round of six-party disarmament talks -- involving the two Koreas, China, Japan, Russia and the United States -- is held in Beijing.

2005

- February 10: North Korea declares it has manufactured nuclear weapons for self-defence.

- September 19: At six-party talks, North Korea agrees to scrap its nuclear programme and return to the Non-Proliferation Treaty in return for security and diplomatic guarantees and energy aid.

- November 9-11: New round of talks collapses, with the North insisting that US-led financial sanctions which froze its accounts in a Macau bank be lifted.

2006

- October 9: North Korea tests a nuclear weapon.

- October 31: Following secret talks with his North Korean counterpart, US negotiator Christopher Hill announces the North has agreed to return to the six-party talks.

2007

- February 13: China announces deal under which North Korea will disable nuclear plants at Yongbyon and allow IAEA inspectors to return. In exchange it will get one million tonnes of fuel aid and be removed from a US list of terrorist states.

- July 14: First shipment of fuel aid reaches North Korea, along with IAEA inspectors. US says Yongbyon has been shut down.

- October 3: Six nations announce deal under which the North will declare all nuclear programmes and disable Yongbyon by the end of 2007. Disablement starts in November.

2008

- June 26: North Korea hands over declaration on its nuclear programme.

- August 26: North Korea says it has stopped disablement and will consider restoring the plants in protest at US failure to drop it from the terrorism blacklist.

- October 11: US says it is removing North Korea from its list of state sponsors of terrorism.

- December 8-11: Six-party talks end in stalemate after failing to agree on how to verify the North's declaration.

2009

- April 5: North Korea launches long-range rocket which it says put a communications satellite into orbit. The United States says the launch was actually a missile test.

- April 13: UN Security Council unanimously condemns North Korea for the launch and tighten existing sanctions.

- April 14: North Korea announces it will quit the six-nation talks, reopen disabled plants and strengthen its nuclear deterrent.

- May 25: North carries out a second nuclear test.

-June 12: UN Security Council passes resolution enforcing new sanctions.

2010

- November 12: North unveils uranium enrichment plant to visiting US scientists. Experts say it could be reconfigured to make atomic weapons.

2011

- July 22: North and South Korean nuclear envoys meet in Bali to discuss possible resumption of six-party talks.

- July 28-29: US and North Korea hold similar talks in New York, meet again in Geneva in October.

- December 17: North Korean leader Kim Jong-Il dies and is succeeded by his youngest son Kim Jong-Un.

2012

- February 23-24: US and North Korea hold third round of bilateral talks.

- February 29: North says it will suspend nuclear and missile tests and its uranium enrichment programme.