A car bomb exploded near the headquarters of a major Kurdish party in Baghdad on Tuesday killing four people and wounding 30 others, medical sources said.

"Three Iraqi soldiers and one civilian were killed, and about 30 others were injured in the blast," sources at the Yarmuk Hospital told Xinhua.

The attack appeared to be targeting a passing Iraqi military convoy, sending parts of the vehicle across the nearby Mansour Square outside the Green Zone, a heavily fortified area housing the interim Iraqi government and the US and UK embassies.

Insurgents have been fighting the fledging Iraqi security force, backed by the US army but still poorly equipped and sometimes overpowered by their enemy.

The mid-day blast was also near the Baghdad office of the Patriotic Union of Kurdistan, led by Kurdish heavyweight Jalal Talabani, a front runner for the presidency.

The attack happened as the winning Shiite alliance was meeting in Baghdad to choose their candidate for the premiership. The top two figures bent on getting the post were Ibrahim al-Jaafari, Iraqi vice president and leader of the Dawa party, and Ahmed al-Chalabi, head of the National Congress party.

Leading a Kurdish joint list, the second winner after Shiite alliance, Talabani is widely expected to get the post as president, a largely ceremonial position.

If the goal is achieved, Talabani will be the first Kurdish president of the country.

The US military and Iraqi forces launched a major offensive on Sunday around Ramadi, the provincial capital of Anbar, some 110 km west of Baghdad, in a bid to crack down insurgency.

US and Iraqi authorities have blamed insurgents for their plot to undermine the "peaceful transition of power" between the interim government and the next one after the Jan. 30 elections.