A powerful explosion, triggered by a homemade device placed on a bicycle carrier, caused extensive damage to a shopping center at 292 Kifissias Avenue at Neo Psychico. Two women were slightly injured. According to police, it was a miracle that there were no other casualties, as the spot is usually very busy and there was no warning before the blast, which occurred shortly after 3 p.m. A bus carrying pupils from the Ursulines girls’ school, and which was passing by at the time, had its windows blown out. The young woman attendant was the only casualty when she was hit by shards of glass. The other injured woman was a pedestrian who was knocked down. The attack may have been aimed at an American Express branch which is in the shopping center, although the bicycle was parked at the entrance of the underground car park some distance from the bank, which was closed at the time. Munitions experts were examining pieces of the bomb to determine what it was made of and who might have planted it. The attack differed from previous blasts in many ways: It came without warning and the bomb was placed where it might have killed many victims. The November 17 terrorist organization has always taken steps to try prevent casualties among passers-by in its attacks, while the Revolutionary Cells group always issues a warning by telephone before a bomb attack. This is the first blast in Greece since the September 11 terrorist attacks in America and it comes just two days before the annual commemoration of the day in 1973 in which the military junta of 1967-74 used tanks and troops to crush a student and workers’ uprising at the National Technical University of Athens (Polytechneio). But the explosive device appeared to bear no relation to the improvised bombs made of small gas canisters that small local groups often use on such occasions. The site of the blast was across the road from the Saudi Arabian embassy, raising the possibility that the attack may have been the work of foreign terrorists. Local shopkeepers said that they had not received threats from any protection rackets, apparently ruling that out as a possible motive for the attack. Defamation suit. Costas Laliotis, the general secretary of the ruling PASOK party, said yesterday that he had told his lawyers to file a suit against independent right-wing deputy Giorgos Karatzaferis, demanding 500 million drachmas for what he termed his defamation. Karatzaferis had claimed in an interview that Laliotis, as public works minister, had built a villa for himself in the exclusive suburb of Filothei and was involved in the embezzlement of 14 billion drachmas involving a sports center.