BERLIN — An Algerian man suspected of training with Islamic State terrorists in Syria and of planning an attack in Germany was taken into custody at a refugee shelter in North Rhine-Westphalia early Thursday, as hundreds of police officers carried out raids in three German states, the police said.

Police detained the man, who is 35 years old and was not identified in keeping with German law, along with an Algerian woman whose arrest had been sought on different charges, authorities said.

The Algerian man entered Germany, which took in more than 1 million migrants last year and has been on high alert since the Paris terrorist attacks in November that killed 130 people, at the Bavarian border last fall, the news service DPA reported, citing security sources.

A second Algerian man was also detained in the coordinated raids, which began at 6 a.m. in Berlin, Hanover, and Attendorn, a town of about 25,000 around an hour’s drive northeast of Cologne, said a Berlin police spokesman, Stefan Redlich. Police found two other Algerian men they were seeking — a 31-year-old in Berlin and a 26-year-old in Hanover — but did not take them formally into custody, authorities said.

All four men are suspected of links to the Islamic State and are believed to have been “planning a violent act intended to seriously damage the state,’’ Redlich said.

New York Times