In blocking the appointment of Lord Ashdown as the new UN envoy to Afghanistan, President Karzai has dealt a damaging blow to relations between London and Kabul and set back the cause of the international mission to his country.

For the past two years Britain’s commitment in troops and funding, not to mention the sacrifice of nearly 100 lives, has been focused on helping to stabilise Afghanistan so that Mr Karzai’s fledgeling Government can gradually expand its authority over the lawless regions of the south with the aim ultimately of defeating the Taleban.

This strategy can work only if there is mutual trust between the governments of Britain and Afghanistan. This not only means soldiers fighting side by side in southern Helmand province or officials coordinating antinarcotics strategy and reconstruction efforts, but also a partnership at the highest levels of government.

Speaking at Davos, Mr Karzai suggested that he had lost faith in his British partners. First he criticised the actions of the British military, then he went back on his word and blocked Lord Ashdown’s appointment as UN “super-envoy” to Kabul, a posting that had the backing of the Bush Administration and other Nato partners.

Lord Ashdown was the obvious choice for the job, not because of his nationality but because of his experience. As a former Royal Marine, diplomat and until recently international supremo for Bosnia, the former Liberal Democrat leader is one of the few people qualified to turn around the deteriorating situation in Afghanistan.

An experienced figure of international standing is desperately needed to coordinate both the military and civilian operations in the country. This means persuading reluctant Nato allies to recommit themselves to Afghanistan, where many are seeking to reduce their profile. It also requires improving the lacklustre reconstruction efforts where currently there is duplication, corruption and waste.

The Afghan authorities have suggested that Lord Ashdown was unacceptable because his remit was too powerful.

At a time when President Karzai is looking weak and beleaguered, Kabul may have calculated that Lord Ashdown was overqualified for the job.

The Afghan leader may rue his decision. He is unlikely to find a better candidate to help him to tackle the huge challenges facing his country.

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