Police Lieutenant Thanapat Sirawong said the blaze engulfed the second floor of the embassy's main, colonial-style building, totally damaging the floor and sections of the roof.
Firefighter Niwat Jootawong said "the blaze broke out in a room full of documents and filing cabinets", adding: "That floor is basically burnt down."
The embassy in Bangkok is not the only one where international aid agencies have submitted visa applications, with many using applying through Geneva, London and France.
But Bangkok is the main launchpad into Myanmar for many aid groups and relief workers Al Jazeera spoke to in the Thai city expressed incredulity and annoyance.
Myanmar's military leader Than Shwe agreed last week to allow in foreign aid workers and Ban Ki-moon, the UN secretary-general, led calls on Sunday for Myanmar to make good on that pledge.
Still, Ban said important progress was being made and he was "cautiously optimistic" that a "turning point" had been reached.
Some aid officials were also upbeat.
Anupama Rao Singh, the regional director for Unicef, said she was "optimistic".
"In fact, I'm very optimistic not only because the commitments that have been made but also because Unicef just yesterday we received approval for six of our international staff who have been within the country to actually go and visit the affected area in the Irrawaddy delta. That to me is very exciting," she said.
But all that was before the embassy fire. How much it will slow down the aid effort, already three-weeks delayed, remains to be seen.
French ship rejected
Although the government appears to have soften its stance against international aid workers in recent days, little of the rhetoric has translated to greater access on the ground.
France said on Sunday that it had given up trying to deliver a shipload of aid to cyclone victims, saying it was "shocked" by the resistance of the military rulers in Yangon.
|Ban said he was "cautiously optimistic" that a |
"turning point" had been reached [AFP]
A French military ship with 1,000 tonnes of aid for the battered Irrawaddy delta was instead sent to Thailand to be handed to the World Food Programme for distribution, the defence and foreign ministries said in a statement.
"Nothing... can justify the victims of a catastrophe being denied the basic right to the necessary aid," it said.
The ship, the Mistral, had been poised near the delta to deliver enough aid to help 100,000 people.
The toll from Cyclone Nargis which hit the poor country three weeks ago has reached more than 133,000, with some 2.4 million survivors still short of food, water and shelter and many at risk of dying from hunger or disease.
"Free access [for] experts and international relief workers to the delta zone remains indispensable," said the French foreign ministry's top Asian affairs official Dominique Girard earlier on Sunday.