France is increasing security on flights headed for the United States this summer amid U.S. concerns that al-Qaida is trying to develop a new kind of bomb.

The Obama administration this week called for tighter security measures at foreign airports that have direct flights to the U.S., prompting British airports to increase security Thursday.

The French civil aviation authority on Friday announced stepped-up security measures “for the summer period.” The agency said the measures might cause delays on U.S.-bound flights.

French government officials would not elaborate on the measures, citing the need for discretion in security matters.

One fear is that extremists with a U.S. or other Western passport could carry the new bomb onto a plane undetected by airport security.

At Paris’ Charles de Gaulle airport, U.S.-bound flights saw delays of 30 minutes to an hour Friday. Sophie le Poulennec, a 26-year-old heading to Chicago, said she hoped there weren’t any new luggage restrictions as a result. “I got no information today about this,” she said at the airport.

A U.S. counterterrorism official said this week that American intelligence has picked up indications that bomb makers from Yemen-based al-Qaida in the Arabian Peninsula have traveled to Syria to link up with the al-Qaida affiliate there, known as the Nusra Front.

Olivier de France, a European security expert at France’s Institute for International and Strategic Relations, said expertise already exists to put explosive devices “in anything from shoes, soles, to energy drinks and even possibly surgically implanting these devices.”

What’s different now, he said, is that “this expertise, we fear, might now have proliferated in the direction of Syria and in the direction of Iraq … in the direction of militants who might very well have European passports and therefore might very well have immediate access to trans-Atlantic flights.”

He said the enhanced security measures could involve closer checks of mobile devices and computers. He said they shouldn’t be cause for “any particular hysteria,” and stressed the importance of governments sharing information to increase security.

(AP)