The minister, Giorgos Voulgarakis, was in Washington for talks on efforts to safeguard the games when the bombings occurred May 5, the start of a 100 day countdown to the opening ceremony. Nobody was injured.

"Such events - no matter how small and isolated they are - amount to high treason," Voulgarakis said.

Nobody claimed responsibility for the blasts, but Greek authorities have blamed fringe radical groups.

The attacks raised global concern about Greece's ability to fully protect the Aug. 13-29 Olympics.

On Tuesday, the Australian government upgraded its travel warning for citizens traveling to Greece and noted the "recent series of firebomb attacks."

The security budget for the games has reached $1.2 billion and could rise higher, Greek Police Chief Fotis Nasiakos said.

"It's not unrealistic to say that the security budget will exceed 1 billion euros," said Nasiakos. He said the final figure will not be known until after the Olympics.

The International Olympic Committee wraps up a three-day review of Athens' preparations - including security efforts - on Wednesday.

AP-ES-05-11-04 0901EDT