The prospect of thousands of Turkish troops entering Iraq moved closer on Monday, despite the starkest warning yet from the US to Ankara not to proceed with the plan.
Turkey says deployment will help refugees
US President George W Bush said the US was making it "very clear" to the Turks that they should not cross the border.
But Turkish Prime Minister Recep Tayyip Erdogan, in a nationwide television address on Sunday, made clear that he was planning to go ahead with the deployment.
"The heroic Turkish Armed Forces, the guarantor of peace at
all places and at all times, will once again extend their hand
to those in need of help," Mr Erdogan said.
The presence of Turkish soldiers in the region will be an element of security and stability for Turkey and the region
Recep Tayyip Erdogan
"The presence of Turkish soldiers in the region will be an element of security and stability for Turkey and the region."
He said the deployment would aid refugees and safeguard Turkish security.
Mr Erdogan also said an agreement had been reached with the US - an assertion which Washington has not confirmed.
However, the BBC's Nick Thorpe, on the Turkish-Iraqi border, says a possible compromise may be emerging. Sources say the Turks may seek to advance no further than 20 kilometres (13 miles) into Iraq.
Senior Turkish military figures, including chief-of-staff General Hilmi Ozkok, were travelling to the border region on Monday to meet Turkish military commanders.
The BBC has learnt that more than 10,000 Turkish troops have moved to the border area.
As the tension mounted, the US special envoy to Iraq, Zalmay Khalilzad, was due to hold talks later on Monday with the Turkish Government.
Despite US assurances that it can control events in the north, the issue remains highly sensitive for Turkey. It fears that moves towards an independent Kurdish state in Iraq could spark fresh turmoil in its own Kurdish-populated areas.
BBC correspondent Jonny Dymond says that, despite denials from Ankara, there is little doubt that Turkish forces have infringed the Iraqi border in recent days.
Small numbers of Turkish troops have operated in northern Iraq
since the 1990s, targeting Turkish Kurd rebel groups, but reports in the past week suggested that 1,500 extra troops had been deployed to prepare the way for an even bigger force.
The US has finally abandoned plans for its own land-based invasion of northern Iraq, after months of negotiation and confusion ended in approval only for an air corridor.
US equipment, which had had been sent to Turkey and the eastern Mediterranean for use in the abortive northern front, were reportedly being withdrawn on Monday to begin the long journey to the southern front.
A member of the Turkish parliament, Emin Shirin, told the BBC that his government would "judge what is necessary for the security of Turkey".
"[The Americans] are forgetting our concerns. We are talking about hundreds of thousands of people who could possibly immigrate. I don't think we can trust the Americans on this matter," he said.
He also challenged the US to explain its U-turn on whether a Turkish deployment was desirable.
"About two weeks ago, [the Americans] were completely in agreement to move into Iraq together with us," Mr Shirin said.
"All of a sudden after the Turkish parliament decided to deny the resolution to open the northern border... they find a Turkish presence in the north unacceptable."