PHOENIX - U.S. golfer Tiger Woods' half-brother was arrested for making a bomb threat to the Arizona state government building where he works, in what he described as a joke, Phoenix police said on Friday.

Earl Dennison Woods Jr, 58, threatened to blow up an Arizona Department of Economic Security building in downtown Phoenix on Thursday, said police spokesman Sergeant Trent Crump.

Woods was jailed on suspicion of one count of misdemeanor use of an electronic communication device to terrify, intimidate, threaten or harass, Crump said.

"The call came from a cell phone and the caller stated that he had a bomb and he was going to blow up the building," Crump said.

Woods was released from jail late on Thursday, a Maricopa County sheriff's official said. Terms of his release were not immediately available and he could not be reached for comment.

A spokesman for the Maricopa County Attorney's Office said Woods had not been formally charged with a crime.

"The department can confirm Mr Woods is a DES employee," said Tasya Peterson, a spokeswoman for the agency. "He was involved in an incident that occurred yesterday at one of our offices. The department is reviewing this matter and is unable to release more information at this time."

Police said they were alerted to the bomb threat by building security after the office's front desk received the call. About 100 workers were evacuated as a precaution and the building was searched.

Crump said Woods came forward to management during the search and "admitted that he was the one who called in the threat and that it was done as a joke."

Woods also told police the threat was a joke and later said the same thing to a local television station upon his release.

It was not immediately clear if he has a lawyer.

A state economic security spokeswoman had no immediate comment.