Heavily armed anti-terrorism police swooped on woodland villages northeast of Paris on Thursday in a manhunt for two brothers suspected of being the Islamist gunmen who killed 12 people at a French satirical weekly.

About two dozen helmetted and masked officers carried out house-to-house searches in the village of Corcy, a few kilometers from a service station where police sources said the brothers were sighted in ski masks. Helicopters flew overhead.

The two fugitive suspects are French-born sons of Algerian-born parents, both in their early 30s, and already under police surveillance. One was jailed for 18 months for trying to travel to Iraq a decade ago to fight as part of an Islamist cell. Officials said they were armed and dangerous.