Potential further terrorist attacks expected "these days, weeks": French PM

French Prime Minister Manuel Valls on Monday warned of possible further attacks in French soil and in European countries after deadly shootings and suicide bombings rocked Paris on Friday.

"Terrorism has hit and will hit again these days in the coming weeks. I do not say this to scare. Everyone must be fully aware of that," Valls said.

"We know that more attacks are being prepared, not just against France but also against other European countries," he told RTL radio.

Overnight, French police raided homes of suspected Islamist militants across the country in the wake of the Paris attacks, Valls added.

"We are making use of the legal framework of the state of emergency to question people who are part of the radical jihadist movement, and all those who advocate hate of the republic," he said.

As part of judicial inquiry into Friday's attacks, police raided 168 houses across the capital, Interior Minister Bernard Cazeneuve unveiled.

Altogether 23 people were arrested and 104 others were put under house arrest over the last two days. Police has also seized 31 weapons including rocket launchers during the operation, he added.

"Let this be clear to everyone, this is just the beginning, these actions are going to continue," he told reporters.

Simultaneous shootings and explosions at restaurants, Bataclan concert hall and the national stadium in Paris on Friday night killed 132 people and injured hundreds others.

French President declared three days of national mourning. He will make an address to the joint upper and lower houses of parliament later on Monday at the Palace of Versailles. Enditem