Jerome Corsi, who wrote "The Obama Nation: Leftist Politics and the Cult of Personality," was detained before a visit to one of Nairobi's slums to donate $1,000 to Obama's half-brother from the owner of a conservative U.S. Web site, Time Magazine reported. Reporters found George Obama living in poverty.

The Democratic presidential nominee's father was Kenyan.

George Obama did not talk to reporters Tuesday. But one relative told The Guardian Corsi was lucky he did not come to visit.

"I don't think the people in Huruma would have welcomed him," the relative said.

Corsi's book was not well-received in the U.S. press except among right-wing publications and Web sites. He wrote a simliar attack in 2004 on U.S. Sen. John Kerry, the Democratic nominee that year, called 'Unfit to Command."

In his book on Obama, he also attacked Raile Odinga, now the prime minister of Kenya. He claimed that he was in Kenya at the invitation of Christians worried about the rise of radical Islam.

Kenyan immigration officials said that Corsi should have obtained a temporary work permit before his arrival in the country.