Police yesterday expressed concern about the possible reappearance of a radical leftist terror group after bomb disposal experts detonated a large homemade explosive device that had been planted outside the headquarters of a foreign oil company in a coastal suburb of Athens. Police were alerted early yesterday morning by an anonymous caller who said a bomb had been planted outside the offices of Royal Dutch Shell in Palaio Faliron but could not determine when it was due to go off. Bomb disposal experts rushed to the scene and destroyed the device, causing minor damage to adjacent buildings but no injuries. The device, which comprised 3 kilos of dynamite and a timer inside a plastic toolbox, would have caused a massive blast had it detonated as planned, officers said. It was the composition of the bomb that made police think of the group Revolutionary Struggle, which has not claimed any attacks for several months. According to officers from the police’s counterterrorism unit, the group in question used almost exactly the same materials in several blasts in central Athens over the past few years – on a branch of Citibank in the Athens district of Ambelokipi, the Economy Ministry offices in central Syntagma Square, the Labor Ministry offices on Pireos Street and a riot police van on Petrou Ralli Street. Another possibility is that a lesser-known leftist group, calling itself Enedra (Ambush), was behind yesterday’s blast. According to police, this group too would telephone the police – rather than the press as other groups tend to do – prior to its hits. Police believe that the target of yesterday’s intended blast was the premises of Royal Dutch Shell but also Olympic Properties, a state-backed agency that manages Greece’s Olympic venues. Forensic experts were yesterday examining the remains of the explosive device and a cassette containing closed-circuit television footage of the entrance to the building in a bid to acquire some leads.