A powerful bomb blast that tore through the facade of an Athens nightclub early yesterday, but caused no injuries, appears to have been a revenge attack, police said. The improvised explosive device, made with an estimated 5 kilos of dynamite, detonated just before 3.30 a.m. outside the entrance of a strip club called Mousses on Syngrou Avenue. The explosion blew a hole through the entrance to the club, which was empty at the time, and shattered windows in dozens of nearby offices and apartment blocks in Nea Smyrni, prompting police to temporarily close off surrounding roads. The blast also left a large crater in the ground in front of the club. Police said the owner of Mousses had been charged in the past for plotting the contract killing of one of his business rivals.