Military-ruled Myanmar has begun a nuclear weapons programme with the help of North Korea, a new investigation revealed on Friday, citing an army major defector and years of "top secret material".
A documentary shows thousands of photos and defector testimony revealing its nuclear ambitions and a secret network of underground tunnels, allegedly built with help from North Korean experts, television network Al Jazeera said.
Revelations in the film, made by Norway-based news group Democratic Voice of Burma (DVB) and broadcast by Al Jazeera on Friday, prompted a US senator to abruptly cancel a trip to Myanmar, formerly known as Burma.
Jim Webb was due to fly to the country on Thursday but said it would be "unwise and potentially counter-productive" until there is further clarification on accusations of cooperation with nuclear-armed North Korea.
The findings "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.
DVB, a news service run by Myanmar expatriates, says "evidence of Myanmar's nuclear programme has come from top-secret material smuggled out of the country over several years," Al Jazeera reported on its website.
The years-long investigation included hundreds of files and other evidence from a Myanmar defector, army major Sai Thein Win, who said he was deputy commander of a military factory heading up Myanmar's nuclear battalion.
"They really want to build a bomb. That is their main objective," he is quoted as saying in the film.
Files reportedly smuggled out of Myanmar by Sai Thein Win have been seen by experts including Robert Kelley, former director of the International Atomic Energy Agency, in the film.
"It appears it is a nuclear weapons programme because there is no conceivable use for this for nuclear power or anything like that," he said, according to Al Jazeera.
Myanmar, which has been military-ruled since 1962, has previously been accused of violating a UN Security Council ban on North Korean arms exports, which was imposed last June.
Following a visit there in May, US Assistant Secretary of State for East Asian and Pacific Affairs Kurt Campbell expressed concern about a suspected arms shipment from North Korea to Myanmar.
He 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.
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 20 years -- as well as raising nuclear worries.