Kurdish officials in Iraq say their deputy chief of security in the north-eastern province of Sulaymaniyah has been shot dead by Islamic militant group Ansar al-Islam.
The PUK controls Sulaymaniyah and other parts of northern Iraq
A spokesman for the Patriotic Union of Kurdistan (PUK) said Hama Hussein was killed by four members of the group.
The group is accused by both the Kurds and the Americans of having links with international terrorism and the al-Qaeda movement.
Correspondents say Ansar fighters are thought to be slipping back into Iraq from Iran five months after US forces crushed their bases along the border between the two countries.
Coalition authorities are concerned that foreign fighters
may have hooked up with remnants of Ansar al-Islam, they say.
Earlier on Friday, US Attorney General John Ashcroft was in the Norwegian capital, Oslo, to discuss the case of Mullah Krekar, Ansar al-Islam's alleged leader who is currently facing extradition from Norway where he has enjoyed political asylum.
Diplomats say Washington has been aghast that Oslo has not permanently locked up Mr Krekar, who says Ansar is not a threat.
"Ansar al-Islam is a group in which we have a great
interest, to the extent to which we reject the idea of terror as a means of shaping public policy," Mr Ashcroft said, without giving details of the discussion with his Norwegian counterpart, Odd Einar Doerum.
In Iraq, the Kurdish spokesman said the Sulaymaniyah incident happened after Kurdish forces surrounded a house in the city where Ansar members were involved in a stand-off.
The militants had agreed to meet Mr Hussein to negotiate, but then opened fire on him.
In Iraq, the spokesman said at least three Ansar members were killed in the ensuing clash and another arrested.
A child was caught in the cross-fire and was also killed.
The PUK controls Sulaymaniyah and other parts of northern Iraq and supported the US-led war against Saddam Hussein's government.