US intelligence suspects Afghan President Hamid Karzai has received treatment for manic depression, contributing to the uneasy US ties with him, a new book by legendary reporter Bob Woodward says.

"He's on his meds, he's off his meds," the US ambassador to Afghanistan, Karl Eikenberry, is quoted as saying in the new book "Obama's Wars," according to a pre-release account Monday in The Washington Post.

The paper added that according to US intelligence reports Karzai has been diagnosed with manic depression.

President Barack Obama's administration has had a shaky relationship with Karzai, publicly challenging him last year over allegations of corruption and vote-rigging.

The public criticism has stung Karzai, who has raised eyebrows in Western capitals by accusing foreigners of rigging the election and speaking of the possibility that he would switch to the Taliban.

Eikenberry, formerly the top US commander in Afghanistan, is known to have doubts about Karzai. In a diplomatic cable leaked last year, Eikenberry said Karzai was "not an adequate strategic partner" and questioned the strategy of boosting US troops.

Obama ultimately decided late last year to order another 30,000 troops to Afghanistan, but also to set a goal of mid-2011 to begin handing over security to local forces.

Woodward's book outlined fierce divisions between the White House and the Pentagon, with the military pushing for more troops once the young president took over last year.

Peter Galbraith, a former UN envoy in Afghanistan who was sacked last year after alleging election fraud, last year also raised questions about Karzai's mental stability.