Voting has begun in a snap general election in Greece. Opinion polls put the opposition Socialists led by George Papandreou ahead of Prime Minister Costas Karamanlis' New Democracy party. Mr. Karamanlis was only half way into his four-year term when he called the election in early September. He said he wanted a new mandate to tackle Greece's economic problems. However, the government has been hit by a series of corruption scandals. <br/><br/>