David Miliband and Condoleezza Rice made a surprise visit to Afghanistan today to press their case for more Nato combat troops, mend fences with President Karzai and defend the country’s progress since 2001.

As Nato defence ministers met in Lithuania, the British Foreign Secretary and the US Secretary of State flew together to Kabul, the Afghan capital, and to Kandahar, the birthplace of the Taleban and the main city of the volatile south.

Mr Miliband and Ms Rice, who held talks in London on Wednesday, used the rare joint trip to put on a show of unity in the face of mounting criticism of the international effort to rebuild Afghanistan.

Their main goal was to press reluctant Nato allies to send more troops to southern Afghanistan to fight the Taleban, which was toppled by a US-led invasion in late 2001 but has regrouped and launched a ferocious insurgency.

“Frankly, I hope there will be more troop contributions and there needs to be more Afghan forces,” Ms Rice said on the flight from London, adding that Nato members needed to “give enough military power to do what needs to be done on the front end of the counter-insurgency effort”.

Ms Rice and Mr Miliband emphasised that message by flying to Kandahar on a US military plane and making rousing speeches to some of the British, American and other troops fighting on the front line. “This is a fight which will transform history,” Ms Rice told the troops at Kandahar airfield, adding that their efforts would leave an “extraordinary legacy of peace and democracy”.

Mr Miliband said: “As the debate hots up in our countries about what you’re doing and the difference you’re making, we’ll be defending you heart and soul.”

The pair then returned to a snowy Kabul to meet President Karzai, less than two weeks after he criticised British efforts in southern Afghanistan and blocked the appointment of Lord Ashdown of Norton-sub-Hamdon as a United Nations “super-envoy” for Afghanistan.

In an hour-long meeting at the heavily fortified Presidential Palace in Kabul, they discussed those and other issues, including a death sentence passed on an Afhgan reporter for blasphemy, before presenting a united front at a joint news conference.

Mr Karzai said that he had been misquoted as saying that Britain had made “mistakes” in the southern province of Helmand — Afghanistan’s main opium producer — since its troops deployed there in early 2006. “I didn’t say that ... Britain is the second-largest donor to Afhganistan. It has the second-largest number of troops in Afghanistan. It has had losses of life in Afghanistan. We respect Britain as a country that is delivering assistance to Afghanistan,” he said.

“I’m terribly embarrassed that this has come up. That is not what I said. We appreciate the British role in Afghanistan and the contribution that they have made. Yes, we have all made mistakes over the years ... and we are all trying to correct them and to move forward.”

Mr Karzai expressed regret that Lord Ashdown had not been appointed as the UN special representative for Afghanistan — even though the Afghan leader blocked his candidacy personally, fearing that he would be too similar to a British colonial viceroy. “I’m very, very sorry that Mr Ashdown could not begin his job, that it did not work out,” Mr Karzai said. “It’s a personal matter of unhappiness for me.”

He said that his Government would support whoever the UN Secretary-General selected for the post, which coordinates international military and civilian cooperation.

Mr Karzai and his guests also disputed the conclusions of two reports last week which said Nato was failing in Afghanistan and that the country was reverting into a failed state and terrorist haven. They pointed to improvements in education, infrastructure development and poverty alleviation.

“To say that it’s not working — I think I would say it’s not complete, but the strategy is one that I believe is having a good effect,” Ms Rice said.

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