PARIS — Three days before the start of the 2024 Olympics, France's interior minister said about 1,000 people suspected of possibly meddling for a foreign power have been blocked from attending the Olympics — one of the security challenges that Paris is cracking down on in its goal to keep Games safe for athletes and fans.

About 1 million background checks have scrutinized Olympic volunteers, workers and others involved in the Games as well as those applying for passes to enter the most tightly controlled security zone in Paris — along the banks of the Seine — ahead of the opening ceremony on the river Friday.