Greek media reported that the device had been hidden in a travel bag. The powerful blast shattered windows of nearby homes and was heard in the centre of Athens several kilometres away.

The blast in Korydallos followed a telephone warning to an Athens newspaper, officials said. One report says a woman has been injured in the blast, but this has not been confirmed.

There was no immediate claim of responsibility.

Athens has seen recent violent protests as the government unveiled tough austerity measures in return for a huge rescue package for its debt-ridden economy.