German police say they've arrested a couple on allegations they lured young women seeking romance and then forced them into prostitution in France.

Duesseldorf police said Wednesday that the man and his girlfriend, whose names weren't given, were arrested earlier this month.

Police told reporters that the man, described as a 35-year-old martial arts specialist, lured the women with romantic overtures over social media and through other methods, the dpa news agency reported.

He and his 25-year-old girlfriend are alleged to have forced at least four women, aged 19 to 28, into prostitution in Paris' red light district and earned at least a half-million euros (dollars).

The investigation has been going on for several months after one victim went to police.