Obama's girlfriend said he took the 3-year-old child last month from her home in a Nairobi slum on the pretense of wanting to buy him a birthday present, ABC News reported Wednesday.
The girlfriend's attorney told a Nairobi judge that George Obama wants to take the child to the United States.
The judge barred the 30-year-old Obama from taking the boy from the country and ordered him to bring the child to a court hearing at the end of the month.
Barack Obama Sr. is the father of both the president and George Obama, but they have different mothers. The father died when George Obama was a baby. President Obama is 20 years older than his half brother. The two have met only twice.