Material believed to be an explosive belt has been found in a public litter bin in the town of Montrouge south of Paris, a source close to the investigation sasy.

"It looks like a belt of explosives," the source told Reuters on Monday, adding that checks were underway.

France and Belgium are trying to hunt down suspects and would-be assailants following the November 13 attacks that killed 130 people in Paris.

After the attacks, the mobile phone of one suspected assailant, Salah Abdeslam, was detected in the 18th district in the north of Paris and then later in Chatillon in the south, the source said.