ATHENS (Reuters) - Greek police fired teargas at protesters hurling stones at them during brief clashes on the sidelines of a mass rally against pension reforms in central Athens on Thursday, Reuters witnesses said. Scuffles broke out among dozens of demonstrators and police during an otherwise peaceful march of tens of thousands to parliament, protesting pension reforms pursued by the leftist-led government. (Reporting By Renee Maltezou, writing by Michele Kambas)