The near-simultaneous mid-afternoon blasts targetted two packed upscale shopping centres, the Dagon and Junction Eight, and the downtown Yangon Trade Centre which was hosting a Thai trade fair.

Witnesses have said that dozens of people were killed in the explosions that hit three locations.

A Myanmar national at the Yangon Trade Centre said he also saw scores of bodies there, while a stallholder at the center said there "many casualties" as the bomb hit a fashion show being held on the third floor.

Another witness at the downtown Dagon center, where two bombs exploded, counted at least 20 bodies while a witness at Junction Eight some 13km north of the city centre counted over 40.

But eleven people were confirmed dead and 162 injured in the four bomb explosions officially in state radio report.

Myanmar's ruling junta yesterday blamed three ethnic rebel armies and an exile pro-democracy group for the deadly bomb blasts that hit Yangon, state television reported.

Authorities blamed the rebel Karen National Union, the Shan State Army-South, and the Karenni National Progressive Party, as well as a government in exile known as the National Coalition Government of the Union of Burma, state television said.

"Authorities put the blame squarely on the KNU, the KNPP, the SSA south, and the NCGUB as being the perpetrators of the bombs," the official report said.

The KNU, the SSA-South and the KNPP are among the ethnic rebel armies who have not signed ceasefire agreements with the military government, pushing their battle for autonomy for their regions.

An official from Myanmar's military government confirmed four bombs were detonated but gave no casualty count. Hospitals in Yangon were unable to give a death toll, but said over 200 people were wounded.

"I saw these people in a pool of blood. Some of them had their legs and arms blown off," said a man outside the Yangon Trade Centre.

A survivor of the Dagon blast recalled panicked efforts to escape.

"There was an explosion in the Dagon centre, and we were so frightened we ran downstairs to get out," a young woman told AFP.

A witness at Junction Eight said she counted "at least 40 bodies being brought out of the building".

Military-ruled Myanmar has been at various stages of civil war for decades, with government troops battling several ethnic guerrilla armies, but the capital has not seen an attack on this scale in living memory.

No group immediately claimed responsibility for the attacks.

Staff at Yangon General Hospital said they were inundated with dead and wounded.

"We cannot say how many people are dead, but we have received about 200 injured people," an emergency services official at the hospital said, with the urgent cries of other staff and the wounded echoing in the background.

Several junta officials were seen at the scene of the attacks. Access roads to the bomb sites were blocked by security forces, an AFP correspondent witnessed.

The blasts came on the day Asian and European foreign ministers meeting in Japan urged Myanmar to speed up democratic reforms, but they stopped short of making more specific demands such as the release of opposition leader Aung San Suu Kyi from house arrest.