[Members of the communist-affiliated PAME union take part in a rally commemorating May Day, which was postponed due to the Greek Orthodox Easter, and against tax and pension reforms in Athens]ATHENS (Reuters) - Greek police fired rounds of teargas during a protest outside parliament in central Athens on Sunday evening where lawmakers were discussing controversial tax and pension reforms, a Reuters witness said. A number of hooded protesters threw petrol bombs at police, who responded with stun grenades and teargas, forcing crowds to quickly disperse. (Writing by Michele Kambas)