A previously unknown terror group yesterday claimed responsibility for a firebomb attack on Wednesday night at the central Athens office of Kyriakos Mitsotakis, a New Democracy MP who is the brother of Foreign Minister Dora Bakoyannis. Mitsotakis is believed to have been targeted due to statements he made criticizing rioters who wrecked stores and cars in Kolonaki last Friday. The attack, carried out using a homemade bomb comprising four gas canisters, was claimed by a group calling itself Revolutionary Liberation Action in telephone calls to Eleftherotypia and Skai. The explosion, which caused minor damage but no injuries, went unnoticed by police patrols in the area. Late yesterday police in the central district of Ambelokipi were scouring the area around the Supreme Court and central headquarters of Attica police after reports of a strong explosion at around 9.30 p.m. Initial reports suggested that the blast had been caused by a car bomb.