Three attacks around the capital came one day after US Defense Secretary Donald Rumsfeld warned Iraq's ruling elite against purging their opponents from security services and against corruption.

Near the northern city of Kirkuk, Colonel Natham Abdullah, in charge of protecting the region's lucrative oil fields, and eight soldiers were killed when a bomb blew up while they were defusing another device.

With oil exports from Kirkuk to Turkey shut down by a campaign of sabotage, the defense ministry has created a powerful force to guard Iraq's oil and electricity infrastructure. Thousands of Sunni Muslims have been hired to join the army protection force meant to stop the attacks.

But rebels

rocked the capital with a slew of attacks as Zoellick arrived.

A car bomb blew up close to a US military convoy on the road to Baghdad airport, setting ablaze a military vehicle and five civilian cars.

In neighboring Amariya district, a rebel stronghold, a parked car exploded as a US military convoy passed, wounding four civilians.

Across town, a fuel tanker was hit by a bomb on a road through eastern Baghdad bordering the Shiite slum of Sadr City.

Rumsfeld had paid his ninth visit to the country since the American invasion two years ago. He urged Iraqi leaders to resist the temptation to purge the army and police, which the newly empowered Shiites claim have been infiltrated by Baathists from Saddam Hussein's regime.

The United States exerts considerable sway over Iraq through billions of dollars in reconstruction aid and its training of security forces, but Rumsfeld's comments marked the most public intervention by Washington since the January 30 election.

Rumsfeld, who also refused to put a timetable on the withdrawal of approximately 140,000 US soldiers from the country, Wednesday moved on to Afghanistan - another surprise call - where he is expected to discuss setting up permanent American bases.