US forces keep searching for remaining Taleban forces

In the biggest such clash in more than a year, local troops killed 40 Taleban militants hiding near the border town of Spin Boldak, government sources say.

Six government soldiers were also killed in the fierce battle on Wednesday, the district governor of the area, Said Fazaluddin Agha said.

A serious dispute has erupted over the incident between Afghanistan and Pakistan.

Afghan officials have sent some of the bodies to a town in Pakistan saying they were not Afghans, but Pakistani border authorities have declined to accept them, saying they are not Pakistanis.

The latest fighting comes as Afghan President Hamid Karzai prepares to meet UK Prime Minister Tony Blair for talks on reconstruction efforts in the troubled country.

Resurgence?

Sporadic fighting around Spin Boldak, with suspected Taleban fighters staging hit-and-run missions against local forces, had been going on for about a week, says the BBC's Kylie Morris in Kabul.

But on Wednesday, the battle escalated in Nimakai, a town about 10 kilometres (six miles) north of Spin Boldak, as well as nearby Populzai and Hassanzai.

"We were trying to find these Taleban and we got a tip that they were hiding in these villages," Mr Fazaluddin Agha said.

The local forces numbering 50 called for reinforcements and another 100 soldiers were sent - but no international troops, he said.

In the six hours that followed, the two sides fought using rocket-propelled grenades and semi-automatic weapons.

"This is the first time so many have been killed in an operation since their fall," an Afghan spokesman said.

Khalid Pashtun said he was not troubled by the reappearance of the Taleban in such numbers.

Mr Pashtun said the outcome of the battle will have discouraged them.

In recent days, the US-led coalition has conducted operations near the town of Gardez, where they captured four men who they believed to be connected to the Taleban.

The campaign was launched on the basis of local reports that a senior Taleban official had moved back into the area, accompanied by Arab fighters.

There has also been persistent fighting in recent weeks in the north between key factions.

London talks

During his London visit, Mr Karzai is also expected to discuss plans to draft a new constitution in his country.

He will also call on the international community to provide more financial assistance to Afghanistan.

Mr Karzai (right) needs help rebuilding his country

The British Government has given its support to a provincial reconstruction team in the northern capital of Mazar-e-Sharif and is expected to send 50 military personnel to the turbulent city.

The UK and Afghan leaders will also discuss drugs.

Afghanistan is the world's leading exporter of opium, and its farmers supply 90% of the heroin that hits Britain's streets.

Britain has played a leading role in the counter-narcotics campaign to stop Afghan farmers cultivating poppies.

But this year is still expected to be a bumper crop.