A Kurdish satellite TV station has broadcast a video which it says shows eight Turkish soldiers taken prisoner by Kurdish rebels.

Turkey denies its men were captured, but has confirmed eight of its soldiers were missing after the ambush in Hakkari by rebels of the Kurdistan Workers' Party, or PKK.

The military said it had had no contact with the soldiers after the clash and said 34 rebels had been killed so far in the offensive launched in retaliation for the attack.

If the soldiers were captured that would make it the largest seizure since 1995, when guerrillas grabbed eight soldiers and took them to northern Iraq.

The United States has brokered a tense ceasefire between the two sides, massed on opposite sides of Turkey's border with Iraq.

Turkey's Foreign minister said his country would pursue diplomacy before it sent troops across the rugged frontier and Prime Minister Recep Tayyip Erdogan has met Gordon Brown in London to discuss the crisis.

The West wants to avoid a Turkish attack on what is currently the most stable part of Iraq but Mr Erdogan has insisted that Turkey will not back away if "the necessary military conditions occurred".

He later ratcheted up pressure by telling an investors' conference that Turkey might impose sanctions on exports to Iraq. Turkish exports to Iraq were worth $2.6 billion (£1.27 million) in 2006.

Mr Brown said: "We unequivocally condemn what the PKK has done, both the deaths of army soldiers, the kidnapping of men and the threat and injuries to civilians.

"We will proscribe the PKK and organisations associated with it in the UK. We will step up our counter-terrorism cooperation with the Turkish government to deal with this issue."

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