France is increasing security on flights headed for the United States this summer, amid U.S. concerns that al-Qaeda 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.

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French government officials would not elaborate Friday 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.