French security services have been probing migrant communities from former Soviet republics in an effort to safeguard the Olympics from the ISIS-K militant group, the interior minister said, confirming a Reuters report published last week.

Gérald Darmanin, interviewed in a Le Parisien article published on Tuesday, said ISIS-K was “undoubtedly the most dangerous movement,” though he said authorities hadn’t identified any concrete threat to the Games.

ISIS-K is a resurgent wing of ISIS, named after the historical region of Khorasan that included parts of Iran, Afghanistan and Central Asia.

To counter the danger, Darmanin said security services had “looked particularly at all the people who revolve around the 10 nationalities of the former Soviet Union.”

Last week, Reuters reported that French security services had been racing to address an intelligence blind spot and forge deeper ties with Tajiks, Central Asians and other people from former Soviet republics living in France.

Tajiks and other Central Asians living in the country told Reuters they had received phone calls or other contacts from police seeking information on them and their communities. The previously unreported outreach comes in the wake two major attacks this year that authorities say were carried out by Tajik members of ISIS-K, in Iran and Moscow.

Darmanin also outlined some of the security measures taken by authorities to prepare for Friday’s opening ceremony along the Seine river, a spectacular and complex event.

“We checked all the cellars of the buildings along the Seine on the route of the ceremony. The catacombs were also checked,” he said. “Thousands of manhole covers were welded shut.”

He said the opening ceremony would go ahead as planned as long as there were no major storms. He expected the opening ceremony would be viewed by 2-3 billion people worldwide.