German police say they have arrested three suspects during raids against a group that is believed to have smuggled at least 160 migrants into Germany over recent months.

Federal police spokesman Christian Meinhold said raids were staged in four German states Wednesday. Two suspects were arrested in Berlin and a third in Bad Muskau, on the Polish border, and seven properties searched.

The suspects are believed to belong to a group that smuggled migrants from the Czech Republic and Poland, largely using trucks.

The alleged smuggling took place since August and an investigation was launched in the fall.

Germany saw around 186,000 asylum-seekers arrive last year. That's much lower than the previous two years, but officials say it's still too high and that's due in part to smugglers' activities.