German police say they have conducted raids in several regions and arrested three people in an investigation of four Algerian men who are suspected of planning attacks in Germany and having ties to the Islamic State group.

Berlin police said in a statement that two men and a woman were arrested in the raids conducted in the capital and in two western states, but that those arrests were based on existing warrants in other cases.

Authorities suspect that the four men under investigation had contacts with IS and say that one of them was being sought by Algerian authorities for belonging to the extremist group. They seized computers, cellphones and other material.

Berlin police spokesman Stefan Redlich told n-tv television that the probe started in December.