WRAPUP 7-Troops fire at funeral as Myanmar mourns bloodiest day since coup

(Updates with comment from Biden, EU)

* Troops fire at mourners at funeral

* At least 114 reported killed by security forces on Saturday

* Total number of civilians reported killed passes 450

* Thousands flee after military air strikes near Thai border

March 28 (Reuters) - Myanmar security forces opened fire at a funeral on Sunday, witnesses said, as people across the country gathered to mourn 114 people killed the previous day in the worst crackdown on protests since last month's military coup.

Mourners fled the shooting at a service for 20-year-old student Thae Maung Maung in Bago near the commercial capital Yangon and there were no immediate reports of casualties, three people in the town told Reuters.

"While we are singing the revolution song for him, security forces just arrived and shot at us," a woman called Aye who was at the service said. "People, including us, run away as they opened fire."

Another 12 people were recorded dead in incidents elsewhere in Myanmar by the Assistance Association for Political Prisoners advocacy group on Sunday, taking its total toll of civilians killed since the Feb. 1 coup to 459.

Thousands of villagers in a border area fled to Thailand after military air strikes on one of several ethnic militias that have stepped up attacks since the coup, witnesses and local media said.

There were no reports of large-scale protests in Yangon or Mandalay, which bore the brunt of the casualties on Saturday, Myanmar's Armed Forces Day. But people in Mandalay surrounded a police station late in the evening, accusing the security forces of arson after five houses burned down, residents said.

Reuters could not reach police there for comment.

At least six children between the ages of 10 and 16 were among those killed on Saturday, according to news reports and witnesses. Protesters call the victims "Fallen Stars".

ISOLATION CALL

The bloodshed drew renewed Western condemnation. The U.N. Special Rapporteur for Myanmar said the army was carrying out "mass murder" and called on the world to isolate the junta and halt its access to weapons.

Foreign criticism and sanctions imposed by some Western nations have failed so far to sway the military leaders, as have almost daily protests around the country since the junta took power and detained elected leader Aung San Suu Kyi.

"We salute our heroes who sacrificed lives during this revolution and We Must Win This REVOLUTION," one of the main protest groups, the General Strike Committee of Nationalities (GSCN), posted on Facebook.