According to the International Institute of Strategic Affairs (IISS) think-tank in London, the Kurdistan Workers' Party or PKK which has been fighting for self-rule in southeast Turkey since 1984, currently has between 3,000 and 5,000 fighters.

In comparison, Turkey has an active capability of nearly 515,000 troops in its army, navy, air force and paramilitary, the IISS said in its publication "The Military Balance 2007".

Carina O'Reilly, European editor at Jane's Country Risk, said PKK numbers were well down on the estimated 10,000 fighters that fought in a bloody civil war in mountainous south-east Turkey from 1984 to 1999.

Then, they were equipped with portable anti-tank weapons and surface-to-air missiles, rumoured to have been supplied by Syria, she said. But since a 1999 ceasefire, they have suffered a shortfall in recruits and hardware.

"Right now, they have got next to nothing," she told AFP. "They are not a serious military force. It feels like they're poking a bear with a big stick. I don't think Turkey wants to go in if it can possibly avoid it.

"The PKK is almost goading them. They don't have the military capability to take on the Turkish government. They haven't got the manpower or the kit."

Fadi Hakura, from the Chatham House foreign affairs think-tank in London, agreed the PKK was a weakened force militarily, compared with Turkey, which has F16 fighter jets, Cobra, Black Hawk and Eurocopter helicopters at its disposal.

But he said PKK tactics had evolved as Iraq descended into sectarian conflict after the 2003 US-led invasion.

"Their tactics are similar to Sunni insurgents in Iraq, for instance improvised explosive devices, mines, attacking military units using for example small cells of five to perhaps 10 fighters," he told AFP.

Such "hit and run" tactics had been effective because of the hostile mountainous terrain of southeast Turkey, where military convoys and supply routes can be seen from afar and detection is difficult, he said.

In addition, the Turkish military had a lack of armoured military vehicles which, coupled with the fact that many of the troops fighting the PKK are conscripts and not trained in counter-insurgency, meant casualties were high.

Both analysts said the PKK appeared to be looking to offset its disadvantage by drawing Turkey into a potentially lengthy conflict in harsh terrain, just as winter snows are set to fall.

That would leave Turkey reliant on air strikes and commando raids but the lightly-equipped PKK were more mobile and could effectively "vanish" in mountain passes, said O'Reilly.

As well as affecting Turkey's standing internationally, a Turkish cross-border strike against PKK bases could draw in up to 100,000 Kurdish fighters -- or peshmergas -- in northern Iraq, who are well-equipped and trained in mountain warfare.

They are unlikely to stand by as the PKK, which they tolerate and allow to circulate in northern Iraq, are attacked, O'Reilly said.

Hakura told BBC radio earlier Monday that with more belligerent noises from Ankara, the threat of invasion was "very high", although specific action against PKK camps in the mountains could see minimal impact on civilian life.

"But if they go for far greater all out war against the Kurdish regional authority in northern Iraq, then the impact could be catastrophic, turning the whole northern part of northern Iraq into a whole quagmire of conflict.

"If the Turkish forces cross over the border it undermines the sanctity of the border and creates a very bad precedent for regional powers like Iran, perhaps even Syria, to undertake overt military interference when they deem it necessary," Hakura said.