ANKARA (AFP) - A loud explosion was heard in the Turkish city of Gaziantep late Friday, which the governor's office said could have been caused by jets taking part in the military incursion in neighbouring Syria.

Governor Ali Yerlikaya's office said that no one had been injured or killed, and that no damage had been caused.

"This sound could have been caused by warplanes involved in the Euphrates Shield operation," Yerlikaya said in a statement. "We will give further details later."

Gaziantep province was on high alert with security forces conducting security checks in several areas, the official news agency Anadolu said.

"Our teams continue their search of the city," Gaziantep Mayor Fatma Sahin told Anadolu.

Turkey launched an unprecedented air and ground operation inside Syria on August 24, backing up opposition fighters, with the ultimate goal of cleansing its border of Islamic State group jihadists and stopping the advance of Syrian Kurdish militia forces which Ankara vehemently opposes.

On Friday, the army said one Turkish soldier was killed in clashes with IS while local media said another five soldiers were injured after a jihadist attack in northern Syria.

Tensions are high in Gaziantep three months after 57 people, 34 of them children, were killed in a suicide bombing on a Kurdish wedding in Gaziantep which was blamed on ISIS.

In September, the United States warned of the risk of a terror attack in Gaziantep on businesses frequented by Westerners, including the popular coffee chain Starbucks.