The military officials from the Patriotic Union of Kurdistan (PUK) said two main highways leading south out of Kirkuk were now unusable by Iraqi forces, adding that most Iraqi army units had either pulled back to within the city limits or fled south.

"We have been able to send small units to within five kilometers of Kirkuk. The American airstrikes have been devastating, so most of the Iraqi forces are now in residential areas. They are virtually surrounded," said a top PUK commander who asked not to be named.

He said the small units of US special forces and PUK peshmerga had also been scouting the oil fields that surround the city while US warplanes have continued non-stop sorties over the city.

There were also reports of a PUK troop build-up in the far southeast of the Kurdish zone, where there are frontlines defending the government-held city of Khanaqin. The city is situated around 140 kilometers northeast of Baghdad.

Independent verification of the advances around Kirkuk were not immediately possible, and the PUK has closed off access for journalists to the frontlines around Kirkuk, even though the other main faction in the north -- the Kurdistan Democratic Party (KDP) -- is allowing press access to the frontlines.

However Kurdish smugglers have confirmed that hilltop areas within five kilometers of Kirkuk appeared to be free of Iraqi government troops.

In the past week, Iraqi government troops have abandoned large swathes of territory in the north after their exposed positions overlooking Kurdish-controlled territory came under daily bombardment by coalition warplanes.

Although punishing airstrikes around Kirkuk have continued over the past 24 hours, most of the action on the northern front has been focussed on the other main northern city of Mosul, where the KDP is battling Iraqi government troops.

And with US troops now entering Baghdad, PUK officials here said they may wait for Iraqi government troops inside Kirkuk to surrender and allow a peaceful takeover of the city rather than stage a direct attack.

The PUK has also been keen to play down its obvious interest in the city, amid Turkish concerns that a Kurdish capture of the oil-rich city could help bankroll moves to establish an independent Kurdistan.

SPACE.WIRE