"The EU and Turkey have regularly reiterated that they remain committed to the independence, sovereignty, unity and territorial integrity of Iraq," said Krisztina Nagy, spokeswoman for EU Enlargement Commissioner Olli Rehn.

"We hope that Turkey will continue to play a constructive role in order to reach these objectives and promote regional cooperation," she added.

Condemning the acts of violence by the separatist Kurdistan Workers' Party (PKK) she stressed that "the EU understands Turkey's concerns about the need to fight terrorism".

"Turkey faces the challenge of cross-border terrorist attacks from the PKK," which is on the EU list of terrorist organisations, Nagy said.

But "it is crucial that Turkey continues to tackle this problem through cooperation between the relevant authorities," she added.

Turkey on Tuesday threatened a military incursion in northern Iraq as part of stepped up measures against Kurdish rebel bases there following the deaths of 15 Turkish soldiers in weekend border attacks.

The Ankara government said in a statement that it had given orders allowing for all legal, economic and political measures, "including a cross-border operation if necessary," against a "terrorist organisation in a neighbouring country".

Ankara says the PKK enjoys free movement in northern Iraq and obtains weapons and explosives there for attacks across the border.

It has also accused Iraqi Kurds of tolerating and even supporting the rebels.