Afghanistan hit back at pressure from Western powers for it to crackdown on corruption on Saturday and accused the United Nations envoy to Kabul of seeking to interfere in the formation of the next government.

Washington, Europe and the United Nations have increasingly been putting public pressure on Hamid Karzai, the newly re-elected president, to tackle widespread graft since he emerged as the winner of the country’s disputed elections on Monday.

In a sharply worded response, Afghanistan’s foreign ministry accused Kai Eide, the UN envoy, of breaching international norms after he called a news conference this week to urge Mr Karzai to appoint reform-minded ministers.

“Over the last few days some political and diplomatic circles and propaganda agencies of certain foreign countries have intervened in Afghanistan’s internal affairs by issuing instructions concerning the composition of Afghan government organs and political policy,” it said. “Such instructions have violated respect for Afghanistan’s national sovereignty.”

The statement also appeared to be directed at Gordon Brown, the British prime minister, who gave a speech on Friday describing Afghanistan as a “byword for corruption” and warning Mr Karzai he risked losing international support. “Cronies and warlords should have no place in the future of a democratic Afghanistan,” Mr Brown said.

Barack Obama, the US president, said on Monday he had telephoned Mr Karzai to urge him to act “swiftly and boldly” to tackle graft.

The foreign ministry’s response will raise concerns over renewed tensions in relations between Mr Karzai and Western governments struggling to justify mounting casualties among Nato forces to voters.

Massive fraud at the August 20 polls and concerns that Mr Karzai will award positions to ex-guerrilla commanders accused of corruption, human rights abuses and drug trafficking have fuelled further disquiet among US and European politicians.

At a news conference on Thursday, Mr Eide called for a “vigorous fight against corruption, efforts to improve the justice system and remove the culture of impunity”.

He also said “we can not afford any longer a situation in which warlords play their own games”.

Mr Karzai pledged to remove the “stain” of corruption from Afghanistan after he was declared winner of the poll following the withdrawal if his main rival from a planned run-off, although he gave no specifics.

The foreign ministry acknowledged the importance of fighting corruption to creating a stable Afghanistan. Nonetheless, it said Mr Eide’s remarks “regretfully crossed the accepted international norms and his authority as an impartial international authority”.

The latest spat between Afghanistan and its Western allies comes against a backdrop of deteriorating security in the capital, which has prompted the UN to temporarily withdraw hundreds of international staff and move others to more secure locations in Kabul.

Separately, the Afghan defence ministry said Nato-led forces mistakenly killed seven Afghan soldiers and police in an air strike while searching for two US paratroopers who went missing earlier this week in western Afghanistan. The Nato-led force confirmed it had launched air strikes during the search but said it was still investigating the report.

Five international troops were wounded, along with at least 20 Afghans, in a battle that took place on Friday during the search operation, a spokesman for the force said.

The Taliban says it is holding the bodies of the two soldiers from the US 82nd Airborne Division who police said drowned in a river during an airdrop of supplies in Badghis Province on Wednesday.