Bombs exploded at employment offices in three Spanish cities yesterday, damaging property but causing no injuries in attacks blamed on the shadowy Marxist group known as GRAPO. Firefighters said somebody had telephoned to claim responsibility in the name of GRAPO for an explosion at the southern city of Seville. Other blasts hit temporary employment offices at Vigo in the northwest and Valencia in the east. Two Molotov cocktails also damaged bank buildings in Seville yesterday. Police in Vigo said GRAPO was under suspicion for the attack in the city because the group had claimed credit for the brazen robbery of an armoured van there in May, killing two guards. GRAPO, which stands for the First of October Anti-Fascist Resistance Group, was active mainly in the late 1970s following the 36-year dictatorship of General Francisco Franco. It was blamed for dozens of assassinations in its campaign to create a Marxist state.