Turkish PM Recep Tayyip Erdogan is in Washington for what Ankara has called a decisive meeting with President George W Bush on Kurdish rebels in north Iraq.

Turkey has threatened to send troops across the border to hit bases used by the Kurdish PKK rebels unless the US and Iraq do more to stop attacks.

The Turkish government is under public pressure to use force against the PKK (Kurdistan Workers' Party).

But Washington has urged Ankara not to launch cross-border strikes.

Impatience

Before leaving for Washington, Mr Erdogan warned that the meeting came at a critical time.

"Our visit comes at a time when [Turkish-US] relations are undergoing a serious test," Mr Erdogan told reporters on Saturday, before departing from Istanbul.

"We have run out of patience with the terrorist attacks being staged from northern Iraq," he said, expressing hope that his talks with Mr Bush would produce "concrete measures".

In spite of promises of action from the Iraqi government and the US, who regard the PKK as the "common enemy", Mr Erdogan did not seem reassured.

On a stop in Italy on his way to Washington he told the newspaper La Repubblica "there hasn't been any concrete step" from the US administration to stop Kurdish violence.

'No safe haven'

Speaking to reporters, White House spokeswoman Dana Perino stressed that Turkey was a "long-running ally" of the US and that Washington wanted to cooperate with Ankara.

"We are concerned about the challenge posed by the PKK terrorists," she said.

"They should be eradicated, and so we will work with Turkey and the Iraqis to make sure there is not a safe haven established for the PKK in that region."

Kurdish protesters demonstrated outside the White House on Monday, voicing their opposition to Mr Erdogan's position.

The Kurdish rebels have intensified their campaign during the past month, killing at least 40 people, military and civilians, in Turkey.

The PKK has waged a violent campaign in the south-eastern region of Turkey since 1984, resulting in more than 30,000 deaths.

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Turkish PM Recep Tayyip Erdogan