In his new book "Duty: Memoirs of a Secretary at War", which leaked to top newspapers, Gates described the United States as a fake supporter of democracy.

The veteran Washington Republican said the 2009 election was "ugly" and that the US made a clumsy attempt to eject Karzai

"It was all ugly: our partner, the president of Afghanistan, was tainted, and our hands were dirty as well," Gates wrote. "Our future dealings with Karzai, always hugely problematic, and his criticisms of us, are at least more understandable in the context of our clumsy and failed putsch."

"Holbrooke was doing his best to bring about the defeat of Karzai," Gates wrote, referring to late US diplomat Richard Holbrooke, who was special envoy for Afghanistan and Pakistan from 2009 to 2010.

"What he really wanted was to have enough credible candidates running to deny Karzai a majority in the election, thus forcing a runoff in which he could be defeated."

The Afghan president has long claimed the US tried to manipulate the election in order to remove him from power.

"There was no exaggeration on our side when talking about this, and now a very senior US official is accepting this fact and talking about it," Karzai's spokesman said on Friday.

"As they say, 'once bitten, twice shy'. That's why, because of this bad experience of the past, we are trying to make sure we do not allow such interference from outside," Aimal Faizi added.

Gates' book, which reviews the US occupation of Afghanistan, is scheduled to hit bookstores next week.

RA/SHI