NAIROBI, Oct 7 (Reuters) - Kenyan immigration authorities have arrested and plan to deport the U.S. author of a critical book about presidential candidate Barack Obama before a launch in Nairobi, witnesses and local media said on Tuesday.

Jerome Corsi, who penned "The Obama Nation", arrived at a Nairobi hotel to present his book in Kenya, but was quickly whisked away by immigration officials, witnesses said.

"He was walking in and then some immigration officers who were following him snatched him," a hotel worker told Reuters.

"It happened so fast, they just vanished with him."

Obama is revered in Kenya for his paternal roots here and as a flagbearer for Africa on the international stage.

Corsi's book, which critics say is meant to hurt Obama's poll prospects next month, questions whether he could still be using drugs and insinuates the Democratic candidate is Muslim.

Kenyan TV station KTN said Corsi may be sent home due to lack of a work permit.

Kenyan government officials declined to comment. (Reporting by Wangui Kanina; Writing by Andrew Cawthorne; Editing by Matthew Tostevin)

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