The fire was believed to have started from welding sparks during roof repairs, leaving part of the silver-tiled exterior scorched. The opera was closed for the summer and there were no casualties.
``It looked pretty bad at the beginning,'' as a large column of smoke rose from the building, fire department spokesman Albert Lehmann said. Seventy firefighters battled heavy smoke to extinguish the blaze, which was put out within 2 1/2 hours.
The opera's stage area was damaged by smoke and water, city spokesman Friedhelm Frechen said, estimating damage at $308,000.
It wasn't immediately clear whether the damage would affect a Ludwig van Beethoven festival scheduled for Sept. 8 at the opera house in the city where he was born in 1770.
The boxy structure on the banks of the Rhine river was built in 1965 and was a favorite of politicians and diplomats in the decades when Bonn was West Germany's capital.
