Turkish authorities suspect a high-profile British jihadist detained in Turkey last week may have been planning attacks in Istanbul similar to those in Paris, two security sources told Reuters on Sunday.
A man thought to be Aine Lesley Davis, an associate of the Islamic State militant dubbed "Jihadi John," was detained in Istanbul last week, senior Turkish officials said on Friday.
Davis was detained with a group of others who could have been planning an attack in Istanbul in parallel with the gun and bomb rampage in the French capital which left at least 129 people dead, a separate source said on Sunday.
"Davis is a figure with key responsibilities within Islamic State and he wasn't caught alone. He was within a group," the source said.
"Right now we're investigating whether they were planning an attack in Istanbul similar to the one in Paris. We suspect there could have been a parallel attack with Paris, on the same day."
Davis is one of a group of British Islamists believed to have been assigned to guard foreign prisoners by Islamic State, alongside Mohammed Emwazi, nicknamed Jihadi John after appearing in videos showing the killings of U.S. and British hostages. Emzawi is thought to have been killed in a drone strike in Syria, U.S. and British officials said on Friday.
Istanbul is one of the world's most popular tourist destinations, with more than 10 million people visiting sights including the Blue Mosque and Hagia Sofia each year.
Separately, the source said eight people suspected of links to Islamic State were detained in Ankara on Sunday, but declined to give their nationalities.
Last month the Turkish capital was rocked by a double suicide bombing on a pro-Kurdish peace rally, which killed more than 100 people. It was the worst attack of its kind in Turkish history and was carried out by Turkish nationals with links to Islamic State, Turkish officials have said.
The detentions are the latest in what many of Turkey's Western allies see as a belated crackdown on Islamist activity inside the NATO-member, which borders both Iraq and Syria.
In July, the Turkish government stepped up its fight against the militants, launching air strikes and opening its air bases to the U.S.-led coalition, a move which increased the risk of reprisal attacks.
A senior government source said Turkey has detained more than 1,000 people suspected of having links with Islamic State this year, and that 300 of them now face court proceedings.
(Reporting by Orhan Coskun, writing by Jonny Hogg; Editing by Digby Lidstone)