BERLIN: German police have arrested two Algerians they suspect of links to the Daesh group and are hunting for two others in operations in Berlin and other regions, they said Thursday.

The police conducted raids in Berlin and other parts of northern Germany on Thursday in a search for four men suspected of links to Daesh militants and possibly preparing an attack in Germany, police said.

One of the two arrested is sought by Algerian authorities for his links to Dash, police said.

“Investigations show that he has been trained militarily in Syria,” they said in a statement.

The second Algerian was arrested for having falsified identity documents. A woman was also detained in the course of the raids, although police did not specify the reason for the arrest.

Some 450 officers took part in the operation sweeping Berlin, and the states of North Rhine-Westphalia and Lower Saxony.

Since the November Paris attacks in which Daesh gunmen and suicide bombers attacked Paris nightspots, killing 130 people, German authorities have issued terrorism alerts on several occasions.

In November, a Germany-Netherlands football match was called off and on New Year’s Eve, several Munich subway stations were closed over such threats.

Mass-selling daily Bild said there were indications that the suspects may have planned to attack Alexanderplatz, a busy transport hub in central Berlin close to the television tower, a top tourist attraction and Germany’s tallest building.

Citing an investigator, Bild said that two of the suspects had apparently recently worked at Alexanderplatz to gather information about the possible target for attack.

Berlin state prosecutors declined to comment on the report. Berlin police were not immediately available for comment.

In close cooperation with the domestic intelligence agency, police arrested two men and one woman on existing warrants related to other matters, they said. German media reported that those arrested were militants.

Fears about an attack on German soil have risen since deadly bombings and shootings in Paris in November.

Thursday’s raids, carried out in part by special forces, took place on four flats and two offices in Berlin and also in properties in North Rhine-Westphalia and Lower Saxony. Police seized computers, mobile telephones and sketches.

One of the suspects is wanted by Algerian authorities, who believe he is a member of Daesh, said the Berlin police. He is suspected of having military training in Syria.

Police in Dortmund said they had conducted an operation in the small town of Attendorn in North Rhine-Westphalia but a spokesman declined to give further details. German media reported police as saying that the main suspect was arrested in a shelter for migrants in Attendorn.

German authorities have repeatedly warned of the threat of attacks. They cancelled a friendly international soccer match in Hanover last year and closed stations in Munich at New Year due to security concerns.