Britain favours cutting back its troop numbers in Afghanistan progressively until 2014, when most foreign combat forces are due to pull out, Prime Minister David Cameron indicated on Tuesday.

Cameron had to abandon plans to land at Camp Bastion, the main British base in Afghanistan's violence-torn Helmand province, because of a severe dust storm. His C-17 transport plane was diverted to the NATO base at Kandahar.

Western countries plan to remove most combat troops from Afghanistan by the end of 2014, but Britain, like the United States, has not yet set out troop reduction plans beyond 2012.

It is an ongoing conversation between allies ... about how exactly transition is progressing and what is the right way to reduce troop numbers effectively between 2012 and 2014, Cameron told reporters on his pre-Christmas trip.

I don't want to see some massive cliff edge in 2014, he said, meaning a very sharp drop in troop numbers. But I don't think we need to make hard and fast decisions right now about precise numbers.

The prime minister has committed Britain to pulling out 500 soldiers next year, cutting its contingent to 9,000, before a complete withdrawal in three years' time.

I am absolutely clear the British public deserves to know there is an end point to combat operations and that end point is the end of 2014, he said.

Officials say the government is looking at various options to reduce troop numbers. One recent report in the Guardian newspaper set out three options: to cut 4,000 troops in 2013, to cut 2,500, or to freeze troop numbers until the end of 2013.

PILOTS

On a bitterly cold day, Cameron spoke to British pilots and ground crew operating Tornado fighter-bombers, part of the 400-strong British contingent in Kandahar, and peered into the cockpit of one Tornado. He also held talks with U.S. General James Higgins, the NATO military commander in the south.

More than 390 British soldiers have been killed in Afghanistan since 2001, the largest death toll of any foreign force apart from the United States.

Discussions between allies on troop reductions would take place at a NATO summit in Chicago next year, Cameron said.

I think we need to coordinate very closely in the buildup of the Afghan national security forces, he said, adding that British forces would not backfill areas left by NATO partners.

I think you are seeing this transition taking place and I am confident that the buildup of the Afghan army will proceed.

Cameron also spoke to Afghan President Hamid Karzai by phone from Kandahar, and discussed reconciliation with the Taliban and the importance of the relationship with Pakistan, British officials said.

Karzai is expected to visit Britain early next year, rescheduling a trip he cancelled this month because of bomb attacks in three Afghan cities that killed at least 80 people.

Pakistan pulled out of an international conference on the future of Afghanistan this month, after a NATO attack killed 24 Pakistani soldiers.

On the prospects of encouraging Taliban insurgents into a political process, Cameron told reporters it was always a difficult process to have reconciliation between enemies.

We saw that in Northern Ireland ... but I am confident there are quite a number of separate developments under way that give me some confidence, he said, without giving details. These efforts had to be Afghan-led, he said.

(Editing by Daniel Magnowski and Ben Harding)