Greek police suspect leftists or anarchists were behind bomb attacks in Athens and the northern city of Thessaloniki.One woman was slightly injured in the blast in the capital, which caused extensive damage to the stock exchange. The police had evacuated the area after an anonymous warning to a Greek newspaper. Other buildings and nearby cars were also damaged. The owner of a nearby cafe said he saw a flash and then felt the force of the explosion, which he said almost knocked him over. Greece has been hit by a spate of similar attacks since 2008 when the fatal shooting by police of a teenager sparked the country’s worst riots in decades. Police say the make-up of the bomb was similar to others planted by a leftist militant group. A smaller bomb exploded in Thessaloniki around the same time. No one was injured in this attack and the blast caused only minor damage to a government building.