PARIS (AP) — Two Frenchmen suspected of plotting terrorist attacks, making explosives and extremist activity online were detained Thursday, amid heightened concern about threats to France over its military campaign against al-Qaida-linked fighters in Mali.

Officials at the Interior Ministry and the Paris prosecutor’s office say intelligence and police officers detained the young men Thursday in a house in Marignane near the Mediterranean port city of Marseille. Authorities were scouring the house for explosives or other evidence of terrorist connections. The suspects are French citizens, aged 18 and 20, the officials said.