Bag thrown into US Embassy compound in Slovenia

A man threw a backpack into the U.S. Embassy compound in Slovenia on Wednesday, triggering a bomb alert, but no explosives were found.

Police arrested a man from Slovenia, and said he apparently considered his action a joke.

But U.S. officials criticized police for reacting slowly at a time when security has been stepped up at U.S. and European embassies around the world after U.S. forces killed al-Qaida leader Osama bin Laden in Pakistan.

The 29-year-old man from the eastern town of Krsko, whose name not released, could face charges of "endangering the security of persons under international protection," said senior police official Janko Gorsek.

"Although this apparently was a bad joke, such behavior must not be allowed and that is why there could be elements of criminal action in his act," Gorsek said.

The U.S. Embassy in Ljubljana, Slovenia's capital, said in a statement that it took the incident "very seriously," even though no explosives were found. The backpack was thrown through a metal fence containing bars that stands about 10 feet (three meters) tall.

The embassy said the incident should "serve as a wake-up call that even in safe Slovenia, bad things could happen." It criticized the police reaction as "slow," adding that it "reminds us that we all need to raise our level of vigilance."

"Greater awareness and vigilance on the part of the authorities and the general public is the best way to combat vulnerabilities," said the statement.

The area around the embassy was cordoned off for few hours early Wednesday while police searched for, then destroyed, the suspicious backpack.