President Obama has several half-siblings by his father
Barack Obama's half-brother was denied entry to the UK after being accused of a serious crime on an earlier visit, the Home Office has confirmed.
Samson Obama, who lives in Kenya, was on his way to the US presidential inauguration in January when he was stopped at East Midlands Airport.
According to the News of the World, fingerprint tests linked him to an alleged sex attack on a British girl.
He was questioned but not charged over the incident in Berkshire, it added.
A Home Office spokesman said Samson Obama was denied a visa after immigration officers noticed one of his documents was false. That led them to further inquiries.
Samson Obama, who runs a mobile phone shop outside Nairobi, had been planning to make a short break in the UK on his way to Washington.
He eventually took a connecting flight to the US without formally entering the UK.
A UK Border Agency spokesman said in general, Britain would oppose the entry of individuals where their presence was "not conducive to the public good".
Samson Obama is one of several half-siblings of the US president.
Barack Obama Sr left his son when he was two years old and lived most of his life in Kenya, where he fathered a number of other sons and a daughter with three other wives. He died in a car crash in 1982.