Greek protesters threw stones and firebombs at riot police who responded with tear gas in Athens on Friday as clashes erupted on the sidelines of a protest against new austerity cuts.

Television footage showed youths in hoods and motorcycle helmets breaking masonry around central Syntagma Square and throwing stones at police, who responded with bursts of tear gas.

One person lay prone on the square, apparently injured in the clashes.

"Protesters threw stones and firebombs at police in at least two locations during the protest," a police source said.

Around 7,000 people were demonstrating at the time in the demonstration that came as unions launched a 48-hour general strike to protest further austerity steps in the country.

Greece's three-party coalition agreed Thursday to a new round of actions to pave the way for a 130-billion-euro (172-billion-dollar) EU bailout ahead of a loan repayment on March 20 which Athens cannot meet without assistance.

According to reports and party leaks, the measures include a 22 percent cut in the minimum wage, a 15 percent cut in complementary pensions and 15,000 civil service redundancies to meet a target of 150,000 layoffs by 2015.