Turkey has begun deporting captured Islamic State (IS) militants, with 11 French jihadists expected to be sent home in the coming days.

State media reports an American foreign fighter was deported on Monday morning, and a spokesman for Turkey’s interior ministry was quoted as saying seven Germans will soon also be repatriated.

Interior Minister Suleyman Soylu had warned last week IS militants would be sent to their home countries even if their citizenships have been revoked.

As many as 2,500 militants could be sent back by Turkey, with the majority going to European Union nations, state broadcaster TRT Haber said, adding there were currently 813 jihadists at 12 deportation centres in the country.

“One American foreign terrorist fighter whose proceedings are completed has been deported,” ministry spokesman Ismail Catakli was quoted as saying by state-run Anadolu news agency.

“Travel plans for seven foreign terrorist fighters of German origin at deportation centres have been completed, they will be deported on Nov. 14,” he added.

"Proceedings concerning 11 foreign fighters of French origin are ongoing," he added.

Broadcaster NTV quoted Catakli as saying that “three more Islamic State militants at deportation centres will be sent back today.”

IS prisoners a 'big threat to Britain and to Europe'

The repatriations follow Turkey’s offensive into northeast Syria against Kurdish YPG militia last month, when US president Donald Trump withdrew his troops from the region.

The YPG, the main element of the Syrian Democratic Forces (SDF) and a US ally against Islamic State, has kept thousands of jihadists in jails across northeast Syria.

The Turkish offensive prompted widespread concern over the fate of the prisoners, with Turkey’s Western allies and the SDF warning it could hinder the fight against Islamic State and aid its resurgence.

MORE: Why is Turkey fighting Syria's Kurds and how is the US involved?

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Ilham Ahmed, a Kurdish political leader and co-chair of the Syrian Democratic Council (SDC) executive, has warned the EU could soon face a wave of Islamic State militants arriving in Europe.

“The threat is very big due to the arbitrary way in which the United States has withdrawn. This has allowed many (Islamic State) members to escape and they will make their way back to their countries to continue their terrorist activities.”

“This poses a big threat to Britain and to Europe in general,” Ahmed added.

Turkey has repeatedly called on European countries, including France, to take back their citizens fighting for the jihadists.

Europeans comprise a fifth of the around 10,000 Islamic State fighters held captive in Syria by Kurdish militias. Denmark, Germany and Britain have so far revoked some citizenships.

Last week, Turkish President Recep Tayyip Erdogan was cited as saying that there are 1,201 Islamic State prisoners in Turkish jails, while Turkey had captured 287 militants in Syria.

The United States said last month that it had killed Islamic State’s leader Abu Bakr al-Baghdadi in northwestern Syria. Last week, Erdogan said Turkey had captured 13 people from Baghdadi’s close circle, adding that they were being interrogated.