ANKARA, Turkey -- Turkish police detained a man after receiving a hoax tip that he was plotting to kill President Barack Obama but quickly released him without charge, a government official said Tuesday.

The official, who is close to police operations in Turkey, said police detained the suspect -- a Turkish national -- on Friday after receiving an anonymous e-mail which even gave the suspect's address in Istanbul. He spoke on condition of anonymity because of rules that bar civil servants from speaking to the media without prior authorization.

"There was nothing serious. Police released the man and said he was mentally disturbed," the official said. "The tip turned out to be a hoax. The IP address from which the e-mail was sent was traced to the United States."

U.S. Secret Service spokesman Ed Donovan said Monday the president was never in any immediate danger. White House spokesman Robert Gibbs, who was with Obama in Istanbul on Tuesday, declined to comment on the incident.

Obama did not arrive in Turkey until Sunday, two days after the man's arrest.

"There was no threat to Obama's life," the Turkish official said. "But the police naturally took such a tip seriously."

A Turkish newspaper, HaberTurk, had claimed Sunday that the police detained a Syrian national who would have posed as a journalist for Al-Jazeera television and thrown a knife at Obama while he addressed a forum aimed at bridging gaps between the West and the Islamic world in Istanbul.

"That report was false," the Turkish official said. "He had no such plan or capability. He even probably did not know that Obama was arriving."

As standard procedure involving a threat against the president overseas, the Secret Service is following up with Turkish authorities regarding the case, Donovan said.

Turkish authorities deployed around 9,000 officers to protect Obama in Istanbul. Armored personnel carriers blocked several streets on Obama's route on Tuesday as the president toured the city.