Thousands of people rallied in front of parliament in Athens on Sunday, urging Greek Prime Minister Alexis Tsipras to resist pressure from international creditors to accept more austerity in exchange for unlocking billions of euros in bailout funds.

After a weekend spent with close aides working out Greece"s proposals to lenders, Tsipras is due to meet the heads of the European Commission, the European Central Bank and International Monetary Fund, the main creditors, before a broader meeting of euro zone leaders on Monday.

Officials say he is ready to make concessions in some areas but has resisted cuts to pensions that the lenders have demanded to shore up Greece"s battered public finances.