"What we are looking for are effective, efficient measures and we need them urgently," retired General Joseph W. Ralston told reporters after talks with Turkish diplomats, his first since he was appointed as a special envoy to coordinate efforts with Turkey.

"They need to be visible so that not only the Turkish public (but) the American public and the Iraqi public can see that we are very serious about eliminating the threat of terrorism," he added.

His comments came a day after a powerful bomb blast killed 10 people, inlcuding seven children, in Diyarbakir, the main city of Turkey's Kurdish-populated southeast.

There was no claim of responsibility for the blast, but immediate suspicions fell on the outlawed Kurdistan Workers' Party (PKK), which is blacklisted as a terrorist group by Turkey, the United States and the European Union.

Ralston, a former supreme commander of NATO, did not specify what measures were being considered, but told the NTV news channel in an interview that priority lay in cutting the organisation's financial sources, shutting its offices in northern Iraq and capturing its leadership.

He added that he would leave Turkey later Wednesday for Baghdad where he would hold talks with government officials and US military officials, including the head of the coalition forces General George Casey.

One of the issues to be discussed will be the appointment of an Iraqi official as a counterpart for Ralston, he said.

Turkey has already apointed a retired general, Edip Baser, for the task and he was present in Wednesday's talks in the Turkish capital.

Turkey's southeast has seen a significant increase in bloodshed by the rebels since they called off a five-year unilateral ceasefire in 2004.

Turkey has repeatedly complained that Iraq and the United States are too passive in the face of PKK rebels, who use bases in Kurdish-held northern Iraq for mounting increasing attacks against Turkish targets across the border.

"PKK terrorism is a fact that we need to fight jointly. We need to be determined on this issue. There has been an escalation (of violence) recently. This must be prevented," the undersecretary of the Turkish foreign ministry, Ali Tuygan, said after meeting Ralston.

"We said we expect concrete results from our cooperation as soon as possible," he added.

Turkey charges that PKK rebels enjoy unrestricted movement in northern Iraq and are easily able to obtain weapons and explosives.

It has for long pressed US and Iraqi officials to arrest leading PKK members based there.

But both the United States and Baghdad have been reluctant to crack down on the rebels, arguing that they are swamped by the violence in other parts of the country.

"We know Iraq has difficulties of its own, but we have difficulties arising out of Iraq. Whatever Iraq's difficulties may be, the PKK must be stopped," a Turkish official said on condition of anonymity.

Growing impatient, Ankara has even threatened a cross border operation to attack PKK camps in Iraq, a move which Washington has opposed on the grounds that joint action by United States, Turkey and Iraq would produce better results.

More than 37,000 people have been killed since 1984 when the PKK picked up arms for Kurdish self-rule in the country's southeastern corner.