North Korea warned Sunday it would retaliate over what it said was South Korea's "intolerable" campaign to censure it at the UN Security Council for the sinking of one of Seoul's warships.

Pyongyang's broadside came as US Defense Secretary Robert Gates said the North might stage more "provocations" while being held to account for the sinking, which has inflamed cross-border tensions.

Seoul has called on the Security Council to respond to the alleged torpedo attack by the North on the the Cheonan warship in March, which claimed the lives of 46 sailors.

The North's Committee for the Peaceful Reunification of the Fatherland said Seoul would suffer a "stern punishment" for its diplomatic drive, describing the campaign as a "conspiratorial farce".

"This is another intolerable and grave provocation to us, and a reckless challenge to the public opinions at home and abroad," the committee, which handles relations with the South, said in a statement.

"The South Korean puppets will never avoid a stern punishment by our military and people, and also strong protests from the southern people if they continues the smear campaign against the DPRK (North Korea)."

It did not not elaborate on what the punishment would be.

South Korea on Friday formally asked for the UN Security Council to take up the matter after a multinational probe found last month that a North Korean torpedo sank the warship.

Seoul said it wants the 15-member body to "respond in a manner appropriate to the gravity of North Korea's military provocation in order to deter recurrence of any further provocation by North Korea".

Gates, who met counterparts from Japan and South Korea on the sidelines of an Asian security conference that ended in Singapore Sunday, called for a united front but admitted Washington and its allies had limited options.

In an interview with the BBC released Sunday, Gates said: "As long as the regime doesn't care what the outside world thinks of it, as long as it doesn't care about the wellbeing of its people, there's not a lot you can do about it, to be quite frank, unless you're willing at some point to use military force.

"And nobody wants to do that."

Given the North's volatile reputation, it is "possible there are other provocations to come", Gates said.

The Minju Joson newspaper, an official North Korean mouthpiece, said South Korean President Lee Myung-Bak was engaged in a "conspiracy with US and Japanese masters" against his fellow Koreans.

It reiterated the North's denial of any involvement in the sinking of the 1,200-tonne corvette which was torn apart by a blast near the disputed Yellow Sea border.

The South has announced a series of reprisals, including cutting off trade with the cash-strapped North, in the wake of the deadliest peace-time tragedy for the country since the end of the 1950-1953 Korean War.

Pyongyang has denied any role in the sinking and has responded to the reprisals with threats of war.

In order to secure a UN censure resolution against the North, Seoul must win support from veto-wielding council members Russia and China, which have traditionally been close to Pyongyang.

Russia, which has said it needs "100 percent proof" of the North's involvement, sent a team of naval experts to South Korea last week to review findings of the probe and visit the site of the sinking.

The South Koreans have also asked China to send its own experts but Beijing has not responded, according to media reports.

At a three-way summit last weekend, China's Premier Wen Jiabao resisted pressure from Japanese and South Korean leaders to publicly support the UN move or to condemn the North, calling instead for calm.

The Yonhap news agency, citing unnamed government sources, said Sunday Seoul was considering sending a high-level envoy to Beijing soon to secure its backing at the Security Council.

Hong Kong's Sunday Morning Post newspaper said Seoul was considering deploying Patriot anti-missile batteries on its soil, a move that would risk angering Beijing,

Officials in Seoul could not immediately confirm the reports.