Media playback is unsupported on your device Media caption John Simpson, in Kabul, spoke to the Taliban spokesman by phone

A spokesman for the Afghan Taliban has said it is "confident of victory" over Nato-led forces and already controls large areas of the country.

Interviewed by the BBC's John Simpson, Zabiullah Mujahed said in remote parts it was "everywhere", and foreign troops were scared to leave their bases.

He also denied any ties with candidates in the "fake" presidential elections.

But it is hard to believe the Taliban might make a comeback in Afghanistan as things stand, our correspondent says.

However, their takeover of Kabul in 1996 was unexpected, and the election of a weak, corrupt president could strengthen them, he adds.

Most Nato-led (Isaf) foreign combat forces are due to leave this year, having handed over control to the Afghan army, as combat operations are declared to be over.

Analysis The Taliban spokesman, Zabiullah Mujahed, seemed to have two aims in his BBC interview - to urge the claim that the Taliban are winning the war and will soon return to power, and to deny any divisions over April's presidential election. The Taliban, he insisted, refused have anything to do with the various candidates in what he called "this fake process", and he strongly denied that some Taliban figures were keen to have talks with the government (though the government insists that this is the case). As things stand, it's very hard to believe that the Taliban might make a comeback. Yet their take-over of Kabul in 1996 was completely unexpected, and happened because the government of the time was so corrupt and ineffectual. If the April election is won by a weak figure suspected of corruption, the Taliban's chances will definitely be boosted. This was the first full interview with the Taliban for 18 months, but it shows that their public relations instincts are as strong as ever.

In December 2013, the head of the British army warned that the Taliban could retake some lost territory after troops leave.

General Sir Peter Wall said the Taliban would fight for land which Nato forces had "suffered significantly" to capture, and that with UK combat forces due to withdraw by the end of 2014, it would be "quite bad news" if some areas changed hands.

Earlier, the US National Intelligence Estimate predicted Afghanistan would descend into chaos if Kabul failed to sign a Bilateral Security Agreement with Washington, which would keep a contingent of US troops in the country after 2014.

'Everywhere is Taliban'

Mr Mujahed said that historically Afghanistan had always defeated its occupiers.

"We're sure they'll be defeated," he said.

"In the remote parts, everywhere is mojahedin Taliban. They're moving around and have control over the villages.

"The foreign forces ... are so scared they're confined to their bases.

He added that "vast swathes" of Helmand province, where UK troops are operating, were under Taliban control.

The spokesman also said that should the group return to power, it would not moderate the extreme methods of government and punishment it employed when last in charge, adding that the "Afghan people will again bring about an Islamic system according to their wishes".

Asked about the elections in April, in which a successor will be chosen for President Hamid Karzai, Mr Mujahed said it was a "fake process".

He said the Taliban had "no relationships" with any of the candidates.

The Isaf force handed security for the whole country over to Afghan forces in 2013 but some 97,000 soldiers remain, of whom some 68,000 are Americans.

But Mr Karzai has delayed signing a security pact with Washington setting terms for some US troops to stay beyond the withdrawal this year.

The current president has served two terms as Afghanistan's first and only president since the Taliban were ousted from power in 2001.