Brussels - Hamid Karzai must rid his new administration of rampant corruption, NATO chief Anders Fogh Rasmussen said Thursday as he hailed the Afghan president's second term as an "historic" event.

"On behalf of NATO, I congratulate President Karzai on taking office for his second term as leader of Afghanistan. This is an historic event: the second time in modern Afghan history that a government has taken office peacefully," the alliance's secretary general said in a statement.

At the same time, the secretary general said "concrete progress" in the fight against corruption was of "critical importance," both to ordinary Afghans and to the international community.

"We strongly support (Karzai's) intention to form a capable and inclusive administration, and to make it accountable, one in which corruption has no place," Rasmussen said.

NATO has been present in Afghanistan for nearly over eight years, helping the Afghan army fight the Taliban insurgency through its International Security Assistance Force (ISAF) mission.

But public support for ISAF has been waning in the West as the Taliban continue to pose a formidable threat to its soldiers.

Americans and European leaders have also expressed disapproval over an election process that was seen as deeply marred by fraud.

Rasmussen said NATO would nevertheless work with Karzai's new government so as to "enable the Afghan National Security Forces to assume lead responsibility for their country's security, district by district and province by province, when conditions permit."

Britain and other NATO allies believe the handover of responsibility should start in 2010. (dpa)