PARIS — French police detained 19 people today as they launched a crackdown on suspected Islamist extremists in cities around the country, President Nicolas Sarkozy said, promising more raids to come.

Tensions are high following a spate of killings in southern France by a radical Islamist that left seven people dead and two wounded and ended up with police killing the gunman last week after a 32-hour standoff.

But French Interior Minister Claude Gueant told journalists “there is no known link” between those detained today and Mohamed Merah, the 23-year-old Frenchman who claimed responsibility for the shootings in Toulouse and Montauban.

Sarkozy gave no details about the reasons for today’s arrests.

“It’s in connection with a form of Islamist radicalism,” Sarkozy said on Europe-1 radio. “There will be other operations that will continue and that will allow us to expel from our national territory a certain number of people who have no reason to be here.”

Sarkozy said he didn’t know whether the 19 detainees were part of any network.

A police investigator told The Associated Press that the anti-terrorist unit of the Criminal Brigade detained five men before dawn in Paris who had suspected links to an Islamist movement. Weapons were also seized, said the official, who spoke on condition of anonymity in line with the department’s rules.

The other arrests took place in Toulouse, Marseille, Nantes and Lyon, the official said.

In Nantes, Mohammed Achamlane, the head of Forsane Alizza, a radical Muslim group that formed two years ago, was among the detained. French officials had banned the group in February.

Merah, who espoused radical Islamist views and said he had links to al-Qaida, was buried near Toulouse on Thursday.

Three Jewish schoolchildren, three paratroopers and a rabbi were killed in the worst terrorist attacks in France since the 1990s, slayings that revived concerns about homegrown Islamist radicals.