Rocket attack on US embassy

A police chief said today a blast at the US Embassy in Athens was an "act of terrorism" caused by a rocket fired from the street.

"This is an act of terrorism. We don't know where from. There was a shell that exploded in the toilets of the building … It was fired from street level," Attica Police chief Asimakis Golfis said.

Police cordoned off streets around the embassy after the explosion smashed glass in the front of the building near the US emblem shortly before 6am local time (4am Irish time).

Traffic came to a standstill across parts of central Athens as police and emergency services scrambled to the embassy building.

Police searched apartment buildings and a hospital near the embassy.

"I heard a loud bang, I didn't realise what was going on," said Giorgos Yiannoulis, who runs a kiosk near the embassy.

The US embassy - a heavily guarded building - is a frequent destination for protest groups.

The embassy confirmed that an explosion had taken place and that no one had been injured.

Investigators found the device used to fire the rocket shell at a building site near the embassy.

US ambassador Charles Reis said the damage was "not extensive".

"There can be no justification for such a senseless act of violence ... The embassy was occupied at the time (but) nobody was hurt," he said.

The shell struck the third floor of the embassy and smashed glass in nearby buildings.

It was the first major attack against a US target in more than a decade, following the arrest of members of Greece's far-left November 17 terrorist group.

The group was blamed for killing 23 people - including US, British and Turkish officials - and dozens of bomb attacks.

In 2003, a special court gave multiple life sentences to November 17's leader, chief assassin and three other members. Lesser sentences were given to 10 others.