US Defence Secretary Robert Gates arrived in Afghanistan on Tuesday, saying he would press President Hamid Karzai to appoint 'honest' ministers but playing down the need for a wholesale government shakeup.

Gates' unannounced visit comes a week after U.S. President Barack Obama approved the deployment of 30,000 extra troops and laid the groundwork for a gradual U.S. withdrawal starting in July 2011 as Afghan forces assume greater control of security.

During his visit, Gates said he would meet US troops and tell them: 'We're in this thing to win.'

Gates said he would tell Karzai and other Afghan leaders that Washington will remain 'their partner for a long time to come' but expected Kabul to get serious about accelerating the training of Afghan forces to prepare for the day when US troops will begin to pull out.

'As the security situation improves and we're able, over time, to reduce our forces, the civilian, developmental, economic, other kinds of relations between us will become the predominant part of the relationship,' Gates told reporters aboard his plane.

Gates will be the most senior US official to meet Karzai since Obama announced his revised war strategy for Afghanistan and Pakistan last week.

Karzai, whose re-election was tainted by rampant fraud in the Aug. 20 vote, pledged in his inauguration speech to name competent and honest ministers. His cabinet is expected to be announced in the coming days.-Reuters