German police said Wednesday they had arrested 11 suspected members of a Nigerian mafia group behind a large-scale dating scam.

The Black Axe gang was involved internationally in multiple areas of criminal activity, with a focus in Germany on romance scams and money-laundering, Bavarian police said in a statement.

The dating trick was a modern form of marriage fraud, police said.

Using false identities, the fraudsters for example signalled their intention to marry and in the course of further contact repeatedly demand money under various pretexts, police said.

The money was subsequently transferred to Black Axe in Nigeria via financial agents, authorities said.

In the process, the gang used a commodity-based money laundering scheme where products, often with a seeming charitable purpose, were bought and delivered to Nigeria.

Some 450 cases of romance scamming had been reported in the region of Bavaria in 2023 alone, with the damages rising to 5.3 million euros ($5.7 million), police said.

The suspects, who all held Nigerian citizenship and were aged between 29 and 53, were arrested in nationwide raids on Tuesday.

Law enforcement swooped on 19 properties, including both homes and asylum shelters, police said.

The Black Axe gang had strict hierarchical structures under leadership in Nigeria operating different territorial units, police said.

The group had a significant influence on politics and public administrations, in particular in Nigeria.

Globally, the gangs main areas of operation were human-trafficking, fraud, money-laundering, prostitution and drug-trafficking.

Black Axe operated under the cover of the Neo Black Movement of Africa, an ostensibly charitable organisation used as camouflage for the gangs structures.

The action against Black Axe was the first of its kind in Germany, police said. (AFP)