Turkey voted in favour of military action against separatist Kurdish rebels in nothern Iraq yesterday, despite strong opposition from the US.

Neighbouring Syria endorsed the move and even Iraq was reported to have said that it would join military action against Kurdistan Workers Party (PKK) separatists hiding in the north of the country.

In a separate development the prospect of a US congressional resolution calling the mass killings of Armenians in 1915 genocide diminished after Democrat sponsors of the measure backed down in the face of pressure from President Bush and Turkey.

Support for the resolution eroded so quickly that Nancy Pelosi, the Democratic House Speaker who earlier this week vowed to bring it to a full vote, said its fate was now in doubt. However, a vote by the Turkish Parliament brought the prospect of military action in northern Iraq closer.

Parliament backed by 507 votes to 19 a motion authorising one or more military incursions within the next year. Ankara says that thousands of PKK separatists train in northern Iraq and mount attacks across the border.

Before the vote President Bush said that it would not be in Turkey’s interests to send troops across its borders and Nato urged its only Muslim member to exercise restraint.

However, Recep Tayyip Erdogan, the Turkish Prime Minister, said: “At the moment it is not important what anybody else says – what is important is what Parliament thinks, and Parliament has made this decision.”

He was backed by the visiting Syrian President Bashar al-Assad. “Without a doubt, we support the decisions taken by the Turkish Government against terrorism and we accept them as a legitimate right of Turkey,” Mr Assad said. Belief that US policy in Iraq is leading to the creation of a separate Kurdish state has given pro-Western Turkey and its neighbours, Syria and Iran – all of whom have restive Kurdish populations – a shared concern.

Iraq, clearly worried by the belligerent rhetoric from across its borders, has promised Turkey that it will crack down on the PKK.

Nouri al-Maliki, the Iraqi Prime Minister, was quoted by CNN Turk television as telling Mr Erdogan that he had ordered regional authorities to act in northern Iraq: “Give us another chance; if necessary let us conduct a joint operation.” Details of the conversation could not be confirmed.

Baghdad is sending a delegation to Ankara this week to follow up a two-day visit by Tariq al-Hashimi, the Iraqi Vice-President, who told reporters that he sensed a softening in the Turkish capital. “I got what I wanted out of these talks,” he said.

“There is a new atmosphere here in favour of resolving this crisis . . . it is mainly Iraq’s business, because the attacks are being mounted from Iraq. But as long as these attacks continue Turkey has a legitimate right to pursue [the] terrorists.”

Turkey has been increasingly dismissive of Washington’s worries over northern Iraq. Ankara reacted with fury last week when the House Foreign Affairs Committee passed a nonbinding resolution saying that Ottoman Turks were guilty of genocide against Armenians in the First World War. But yesterday the number of congressman supporting the measure appeared to drop below a majority.

Mr Bush appeared to have succeeded in convincing enough Democrats that the resolution would greatly damage US national interests, because it would cause Ankara to scale back its assistance in the Iraq war. About 70 per cent of US military cargo into Iraq passes through Turkey.

Mr Erdogan is under pressure to send troops after the PKK. He has implied this is could take the form of bombardment and forays across the border rather than a land offensive.

Times Recommends

• Should Knox’s trial even have reached the courtroom?
• 'Was it real?' The US bailout nightmare
• Iranian opposition plays the long game