Jerome Corsi, centre, was taken to Nairobi's immigration department
Immigration authorities in Kenya have deported the American author of a highly critical book about US presidential candidate Barack Obama.
The author, Jerome Corsi, was in Kenya to launch his book which accuses Mr Obama of supporting an alleged plot to turn Kenya into an Islamic state.
Officials said that Mr Corsi did not have the right visa.
Mr Obama's father was from Kenya, where the US Democratic contender is a highly popular figure.
Mr Corsi - author of The Obama Nation: Leftist Politics and the Cult of Personality - has been accused of a smear campaign against Mr Obama.
In a recent press release, Mr Corsi said he would "expose deep secret ties between US Democratic presidential candidate Sen Barack Obama and a section of the Kenyan government leaders".
Carlos Maluta, a senior Kenyan immigration official, told the AP news agency that authorities had picked Mr Corsi up from his hotel on Tuesday because he did not have the necessary work permit.
Joseph Mumira, head of criminal investigations at Jomo Kenyatta International Airport, said that Mr Corsi was briefly detained at immigration headquarters before being taken to the airport for deportation.
The Obama campaign says on the "Fight the Smears" web site that Mr Corsi listed a number of false claims in relation to Kenya in his book - including that Mr Obama contributed $1m (£570,000) to Kenyan Prime Minister Raila Odinga during Mr Odinga's presidential campaign.
Mr Odinga is from the same Luo community as Mr Obama's father.
The book also repeats false rumours, including that Mr Obama, a Christian, was raised as a Muslim.
Mr Corsi co-authored "Unfit for Command", a book that maligned the Democratic Party's 2004 candidate John Kerry, and is believed to have contributed to his defeat by President George W Bush.