The defence secretary, Liam Fox, wants to speed up the withdrawal of British troops from Afghanistan, saying that Britian is not a "global policeman".

His comments came as he joined the foreign secretary, William Hague, and the international development secretary, Andrew Mitchell, on a trip to Afghanistan to meet political and military leaders in the capital, Kabul.

While Hague indicated that the new coalition government was not planning a strategic break with existing UK policy on Afghanistan, Fox said expectations of Britain's role in the country needed to change. He also risked angering the president, Hamid Karzai, by describing Afghanistan as a "broken 13th-century country".

In an interview with the Times, published ahead of their arrival today, Fox said the goals of the mission in Afghanistan were primarily military rather than humanitarian.

"We have to reset expectations and timelines," he told the paper. "National security is the focus now. We are not a global policeman.

"We are not in Afghanistan for the sake of the education policy in a broken 13th-century country. We are there so the people of Britain and our global interests are not threatened."

Fox said he would like the forces to return to the UK as soon as possible, and ruled out any transfer of British troops from Helmand province to neighbouring Kandahar.

His comments were a contrast to those of Mitchell, who told journalists on the flight to Kabul that development was "absolutely crucial".

"We need to ensure that we help the Afghan people to build a functioning state," he said.

"That's about providing basic education and healthcare facilities, but it's also about ensuring there are opportunities for promoting livelihoods so that people have jobs.

"If we are going to prioritise making sure there is a functioning state in Afghanistan, then development, the work we are doing in that respect, is absolutely crucial."

Aides insisted there were no differences between the three ministers.

Hague told reporters on the flight that "the question is how to support the efforts of the Afghan government and our Nato partners, not whether to support them".

"We are taking stock as a new government, we want to see how things are working, we want to hear the military advice, we want to talk to the Afghan government themselves, we want to discuss the detail with the United States."

The visit was the first to Afghanistan by members of the new government and is intended to reflect the high priority being given to the conflict.

It came as the death of another British serviceman was confirmed yesterday, the 286th in the campaign and the first fatality since the Conservative-Liberal Democrat coalition took office.

On arrival the ministers, all Conservatives, met General Stanley McChrystal, the US commander of Nato operations in Afghanistan, and other military leaders.

Britain has about 10,000 troops in Afghanistan – part of a US-dominated force that is expected to grow to around 140,000 at its height in a few weeks. Washington is sending more troops in a bid to seize insurgent-held areas before a planned withdrawal starting in July 2011.