Greek state television says socialist Prime Minister George Papandreou is offering to form a unity government with the conservative opposition to help win support for austerity measures demanded by international lenders.

NET television says Mr. Papandreou made the offer in a meeting with opposition leader Antonis Samaras on Wednesday. Some conservative lawmakers are calling for the prime minister to resign as part of a power-sharing agreement.

Mr. Papandreou needs parliament to approve new tax hikes and spending cuts in the coming days in return for the next installments of a financial bailout package from the European Union and International Monetary Fund.

His ruling Socialist government saw its slim majority in the 300-seat assembly shrink to just five seats Wednesday after a socialist lawmaker defected to protest austerity plans.

Tens of thousands of Greeks demonstrated against the proposed measures in the cities of Athens and Thessaloniki. The protest in the capital's central Syntagma Square turned violent when riot police fired tear gas at demonstrators who threw stones and fire bombs. At least seven people were injured.

Some protesters tried to form a human chain around parliament to prevent debate on the austerity program, but police set up barricades to allow lawmakers to enter the building.

Major labor unions also staged a general strike Wednesday, crippling Greece's public transit, media and state-run hospitals.