KABUL - Afghan president Hamid Karzai has no plan to install former U.S. ambassador Zalmay Khalilzad as chief executive of his country, a spokesman said on Tuesday, denying a report in the New York Times.

The U.S. newspaper, citing unidentified U.S. and Afghan officials, said Khalilzad, an Afghan-born U.S. citizen who served as former President George W. Bush's ambassador to Afghanistan, Iraq and the United Nations, was discussing taking a powerful post under Karzai.

Because of his influence, Khalilzad was known by many Afghans as Kabul's Viceroy when he served as Washington's top diplomat to Afghanistan.

The newspaper described Khalilzad's proposed future role as chief executive officer of Afghanistan. It quoted a senior U.S. official as saying the post would allow the American diplomat to serve as a prime minister, except not prime minister because he wouldn't be responsible to a parliamentary system.

A spokesman for Karzai said the report was false.

We are not aware of this. We cannot confirm this. There is no truth in it, spokesman Siyamak Herawi said.

Khalilzad is one of several high-profile figures who is said to have contemplated standing against Karzai for president in an election due in August, but like several others he did not register for the election by the May 8 deadline.

A Kabul-based diplomat also said it seemed unlikely Khalilzad would be appointed to such a post.

Karzai has never liked sharing power with anyone and Khalilzad is not Karzai's cup of tea these days, the diplomat told Reuters on condition of anonymity.

Karzai has led Afghanistan since the Taliban's removal from power in 2001 and won the country's first direct vote in 2001.

He has long maintained his authority by giving potential rivals positions inside his government and is believed to have offered senior advisory roles to at least one of the potential challengers who withdrew.

Bringing Khalilzad into Karzai's government in some form would fit that pattern, but there is no constitutional role for a prime minister or chief executive in Afghanistan who could exercise authority independent of the president.

The president appoints all regional governors and other top officials under a strong, centralized system, although some parts of the country are outside the government's control.

As the U.S. ambassador in Afghanistan from 2003-05, Khalilzad played an unusually hands-on role in Afghan politics. Afghans even referred to him as the emir of Kabul and Karzai's boss.

Since those days, Karzai has become more assertive in guarding his image as an independent leader, despite increasing numbers of international troops in the country.

Giving Khalilzad some kind of role in his administration could ease Karzai's relations with the West, which have occasionally been strained. A deal to secure Khalilzad's backing ahead of the election could also undermine opposition candidates.

But giving a high-profile position of authority to a former American diplomat could also anger Afghans, many of whom complain of too much U.S. influence in the country's affairs.

(Writing by Peter Graff; Editing by Paul Tait)