A prominent US Senator abruptly cancelled a trip to military-ruled Myanmar on Thursday after new allegations that the junta is working with North Korea to develop a nuclear programme.

Democratic lawmaker Jim Webb, who had been due to arrive in the capital Naypyidaw late Thursday, released a statement saying it would be "unwise and potentially counter-productive" to visit in light of the latest suspicions.

He had been due to hold talks with detained democracy leader Aung San Suu Kyi and the country's reclusive military junta.

Previous details of possible links between nuclear-armed North Korea and Myanmar, formerly known as Burma, prompted Washington to express concern, even though it has pursued a new policy of engagement with the junta.

"News reports published today contain new allegations regarding the possibility that the Burmese government has been working in conjunction with North Korea in order to develop a nuclear programme," Webb said.

He later told journalists that the documentary, to be aired by news network Al Jazeera on Friday, contained claims by a former Myanmar military officer reported to have "hundreds of files" revealing the junta's ambitions.

Webb also referred to an allegation by US Assistant Secretary of State for East Asian and Pacific Affairs Kurt Campbell last month, on his way out of Myanmar, that the junta had violated a UN ban on all North Korean arms exports.

The alleged violation of UN Security Council Resolution 1874 was "in respect to a shipment that may have contained arms from North Korea to Burma," Webb said at a Bangkok press conference.

"There are now two unresolved matters related to activities of serious concern between these two countries," he said, while stressing that he did not know the validity of the two allegations.

"Until there is further clarification on these matters, I believe it would be unwise and potentially counter-productive for me to visit Burma."

The senator from Virginia, a strong supporter of engaging Myanmar, will now return to Washington on Friday.

He became the first senior US official to meet junta chief Than Shwe in August, winning the release of eccentric American John Yettaw, who was jailed for swimming to Suu Kyi's house.

President Barack Obama's administration last year launched a dialogue with Myanmar's military rulers, after concluding that Western attempts to isolate the regime had met with little success.

But Washington has sharply criticised preparations for this year's elections -- the first in twenty years -- which have been condemned by critics as a ploy to legitimise the military rulers' grip on power.

Following his visit to see top Myanmar officials in May, Assistant Secretary of State Campbell called for "immediate steps" to address fears the polls would lack legitimacy.

He also called for a "transparent process" to be put in place as a way for Myanmar to assure the international community of its commitments to the resolution on North Korean arms.

Myanmar severed ties with Pyongyang in 1983 following a failed assassination attempt by North Korean agents on then-South Korean president Chun Doo-Hwan as he visited the Southeast Asian nation. The attempt left 21 people dead.

But with both countries branded "outposts of tyranny" by the United States they have tried rebuilding relations in recent years.

During a visit to Thailand last July, US Secretary of State Hillary Clinton said North Korea could be sharing atomic technology with Myanmar.

The junta did not make any comment on Thursday.

"I still strongly believe that a continuation of a dialogue between the United States and the government of... Myanmar is very important for the balance in this region," said Webb after cancelling his trip.