France is on high alert after seven hostages, including five French citizens, were kidnapped by the North African wing of al Qaeda last month.

It is reported that one operation focused on a network supplying false papers for jihadists returning from Afghanistan, with police arresting two men in the Mediterranean port of Marseille and a third in the city of Bordeaux.

The three were linked to a man arrested in the Italian city of Naples and suspected of being connected to al Qaeda militants.

In another operation, eight people were said to have been arrested on suspicion of involvement in arms and explosives trafficking. Those arrests took place in a region around Marseille.

Western governments have issued warnings about an elevated terrorism risk in Europe.

The US State Department issued a warning to Americans on Sunday to exercise caution while in Europe. Britain also raised its terrorism threat level to high from general for those travelling to Germany and France.