"Our view is we would prefer to continue to work this problem with them to try and safeguard Turkey and would hope they not take unilateral military action across the border into Iraq," Gates told reporters here.

His comments followed charges by Turkey that Kurdish security forces in northern Iraq had harassed Turkish soldiers and a warning by the Turkish army that Ankara would respond "at the highest level" if it continued.

The Turkish army keeps a contingent of a few thousand soldiers in a region of northern Iraq close to the Turkish border to monitor the activities of Turkish Kurdish rebels holed up in bases in the mountainous region.

Tensions have been rising amid charges that Kurdistan Workers' Party (PKK) rebels have found sanctuary in Kurdish controlled areas of northern Iraq.

"The Turks have a genuine concern with Kurdish terrorism that takes place on Turkish soil," Gates said. "One can understand their frustration and unhappiness over this."

He said retired General Joseph Ralston, a special US envoy on the issue, has been "deeply engaged" with Turkey on the issue.