The top UN official in Afghanistan went beyond his authority by giving instructions on how to rid the government of corruption, the country's foreign ministry said this weekend.

Norwegian diplomat Kai Eide "delivered comments which exceeded international norms and his authority as a representative of an impartial organisation", the ministry said in a statement.

It was strongest indication yet that the administration of President Hamid Karzai will resist prescriptions from the international community on how to rein in corruption or regional power brokers who often wield more power than the government.

International figures including US president Barack Obama and British prime minister Gordon Brown have called for the Afghan government to take concrete steps to clean up the government following a presidential election that was marred by fraud.

The vote took two-and-a-half months to resolve because of ballot box-stuffing and the unwillingness of Karzai and his officials to accept results that would have forced him into a run-off vote. The second round was cancelled when his challenger dropped out.

Eide warned Thursday that the Afghan government should not assume it would have the support of international donors and troops if it continued to be mired in corruption and welcome warlords into the administration.

"We can't afford any longer a situation where warlords and power brokers play their own games," Eide said. "We have to have a political landscape here that draws the country in the same direction, which is in the direction of significant reform."

The foreign ministry condemned such comments as interfering in national sovereignty.