Police were called to the Pennsylvania compound of Fethullah Gulen, the US-based Muslim cleric accused by Turkey of instigating a failed 2016 coup, on Wednesday after a guard fired a shot at a suspected armed intruder, a Gulen spokesman said.

The security guard fired a warning shot as the person tried to enter the compound's gates, and the intruder fled, the spokesman said.

There are no known injuries or arrests, Alp Aslandogan, Mr Gulen's media adviser, told Reuters.

"Just one shot was fired," said Mr Aslandogan. "The person disappeared. The incident is over as far as we're concerned."

Mr Gulen was inside his residence in the compound at the time.