Greece is enduring the second day of a 48-hour general strike in protest of a new round of national austerity reforms.

New clashes Wednesday took place as lawmakers considered Prime Minister George Papandreou's plan to raise taxes, cut government spending and sell state assets.

About 20,000 people had gathered Tuesday in Athens for initially peaceful demonstrations that turned violent. At least 4,000 police officers armed with stun guns, teargas and batons fought the protesters, who hurled rocks and firebombs.

Authorities say at least 14 protesters were arrested, and more than 20 people suffered injuries.

Lawmakers are due to start voting on the austerity measures Wednesday. Greece must adopt the plan by Thursday to avoid default on loans it received last year as part of a $156-billion international bailout, and to collect an $17 billion share of that aid.

Many protesters feel the $40 billion austerity plan imposes harsh penalties on workers and pensioners, while sparing the wealthy.

For a second day the strike has all but shut down Greece.

Transportation, schools and other services were closed Tuesday, as well as many private businesses. Hundreds of flights were canceled or rescheduled as air traffic controllers walked off the job. The air traffic controllers' union said airports would be closed for several hours again Wednesday.

Christine Lagarde, the newly named head of the International Monetary Fund, called on opponents of Mr. Papandreou to support the austerity package, “in the spirit of national unity.”

EU officials have warned that Greece has no choice but to adopt the austerity plan, saying a default would be calamitous for the 17 countries that use the common euro currency and the broader world economy.