New York — Possibly due to his criminal past, the Kenyan half-brother of President Barack Obama could not get a US visa in time for a planned tour to publicise his book.

Delays in fixing a visa application date for Mr George Obama, along with the US embassy's rejection of his publisher's request for an expedited review, may have reflected US officials' desire not to embarrass President Obama by explicitly barring his relative from entering US.

The US embassy in Nairobi may also have been keen not to seem to be giving preferential treatment to a visa applicant that is a blood relation of their president.

Another possibility is that Mr George Obama simply became ensnared in the protracted bureaucratic process familiar to many Kenyans who seek clearance to visit the US.

Under State Department rules, the president's half-brother could have been deemed inadmissible to America for reasons arising from his arrest and detention on separate charges of drug possession and armed robbery.

Citing privacy considerations, the State Department declines, as a matter of policy, to comment on individual visa cases. Asked a few weeks ago to comment on his visa denial, Mr George Obama, who lives in Nairobi's Huruma slum, refused to answer directly. "I didn't feel like going," he said in an interview. "I don't like travelling," he added.

The US embassy was reluctant to comment on the issue. "I'm sorry we do not comment on individuals' visa applications," said Mr John Haynes, the embassy public affairs officer.