Public sector workers in Greece have launched a nationwide strike in protest at government measures to tackle the country's huge budget deficit. Flights have been grounded, many schools closed, and hospitals are operating an emergency-only service. The government wants to cut pay, reduce pensions and revise the tax system. Yesterday,the socialist government announced that it intends to raise the average retirement age in a bid to save the cash-strapped pensions system. Greek Prime Minister George Papandreou has already faced down a three-week protest by farmers demanding higher government subsidies. EU leaders will discuss the issue during a summit in Brussels tomorrow amid concern the Greek crisis could threaten the credibility of the euro. <br/>