French security forces have made nearly 300 searches in the Paris region since the jihadist attacks of November 13, police chief Michel Cadot said on Monday.
A total of 298 searches were made, Cadot said.
He added there were 10,200 police and 6,400 soldiers deployed across the region that includes the capital -- prioritising stations, airports, large public spaces, government buildings, cultural sites, media companies and hospitals.
"The threat level remains raised," said Cadot.
"We see a number of messages from Daesh (an alternative name for the Islamic State group being broadcast on the Internet and which clearly target France."
He said there had been a small number of racist or anti-Islamic attacks, but praised the largely "responsible and Republican" response of the French public.
Under the heightened security alert, schoolchildren will not be allowed to take part in the UN climate conference which starts next week just outside Paris, he added.