Two powerful car bomb blasts in central Baghdad have killed at least 147 people and wounded 500 others in the bloodiest attack in months.

Sunday's near-simultaneous blasts were aimed at a provincial government building and the Ministry of Justice. Iraq's Interior Ministry says the death toll may rise as rescue workers pull bodies from the rubble.

Prime Minister Nouri al-Maliki visited the scene soon after the massive explosions that sent smoke billowing into the sky.

There was no immediate claim of responsibility for the attack. Iraqi government spokesman Ali al-Dabbagh says the violence bears the hallmarks of al-Qaida.

Violence in Iraq has dropped significantly in the past year, but officials have warned that attacks could rise ahead of elections in January.

U.S. President Barack Obama called Mr. Maliki and Iraqi President Jalal Talabani to express his condolences and reiterate U.S. support for the Iraqis.

Mr. Obama condemned the attacks. He said the United States will stand with Iraq's people and government as they prepare for upcoming elections.

U.S. Secretary of State Hillary Clinton called the bombings "despicable terrorist attacks." She said those behind the violence "seek to undermine the impressive progress that Iraq has made towards stability and self-reliance." Clinton said they will not succeed.

And U.N. Secretary-General Ban Ki-moon strongly condemned what he called "senseless and indiscriminate acts of violence." He said the attackers repeatedly target the innocent and aim to disrupt Iraq 's recovery.

Two months ago, attackers targeted Iraq's ministries of finance and foreign affairs. Those truck bombs killed more than 100 people and wounded 500 others. Al-Qaida claimed responsibility for those blasts.