A Greek riot policeman has been seriously injured by two men with Kalashnikov automatic weapons in central Athens, officials say.

The officer was part of a unit guarding the culture ministry when the pre-dawn attack took place.

The policeman was taken to hospital and was undergoing surgery.

A huge manhunt is under way. Last month Greece saw its worst riots in decades after the fatal shooting by police of a teenager in Athens.

Police say 20 shots were fired by the attackers.

They say the 21-year-old officer spotted the gunmen and warned his colleagues shortly before he was hit by two bullets, one in the chest, the other in the leg.

A number of people have been taken in for questioning.

Guns 'link several Greek attacks'
Greek police at the scene of the shooting of a Greek policeman, 5/1/2009
Anger at the police has soared since the shooting of a teenager

Weapons used to shoot a police unit in Greece overnight are linked to two previous attacks, including one by an anti-US militant group, police say.....

.....A group calling itself Popular Action claimed to be behind that attack.

That group operated for almost 30 years with apparent impunity, carrying out two dozen assassinations and countless bomb attacks against mainly foreign targets, says the BBC's Malcolm Brabant in Athens.

Greek police finally captured one of the group's members in 2002. It was disbanded soon afterwards.