French military intelligence estimates that about 100 foreign fighters are entering Syria from Turkey each week to join the Islamic State in Iraq and Syria.
"According to the Direction for Military Intelligence (DRM) in Paris, each week, about 100 foreigners continue to cross Turkey into Syria to join Islamic State," French newspaper Le Figaro reported Wednesday, according to Reuters.
The estimate is likely to raise scrutiny on Turkey's effectiveness as a partner in the fight against ISIS, in particular following a failed military coup attempt last week.
French Foreign Minister Jean-Marc Ayrault said on Sunday that he expected the coalition to raise questions about Turkey's efforts during a meeting hosted by U.S. Defense Secretary Ash Carter in Washington on Wednesday.
British Secretary of Defense Michael Fallon said Wednesday at a breakfast with defense reporters before the meeting that the coup attempt hasn't had a direct impact yet on the ISIS campaign along Turkey's border with northern Syria.
He added that Turkey would not have "any less interest in sealing the border with Syria," but added, "obviously we'll be watching."
In late April, a U.S. military official said about 200 foreign fighters per month were going to fight with ISIS, down from more than 2,000 per month. The U.S. military updated its estimate in late June to between 200 and 500 per month.
This story was updated at 9:55 a.m.