A major investigation has been launched by police in the Netherlands into the suspected drugging and sexual assaults of a number of women, prompting the arrests of four men.

Dutch police said they had received information suggesting multiple women may have been drugged "by someone in their immediate circle" and sexually assaulted on camera, following tip-offs from agencies in England and Germany.

The suspects allegedly frequented private social media groups in which tips were shared on how best to drug victims and images of the abuse were circulated.

The number of victims is not yet clear and more arrests could follow, the national police force said.

Dutch media likened the alleged events to the case of Gisèle Pelicot, whose husband repeatedly drugged her and invited dozens of men to rape her in France.

Police in the Netherlands said on Thursday the arrests were made after they raided the homes of eight suspects - men aged between 21 and 51 identified through the online groups - in late May.

Detectives are now studying computers, USB sticks, SD cards and phones seized during the raids.

Drugs and weapons were also found at some of the locations.

The charges against the suspects vary. They include alleged participation in the online groups, creation or distribution of sexual imagery, and "endangering victims by drugging them, up to and including (attempted) rape".

Milou van der Kolk of the Rotterdam sexual crimes team said it was not yet clear how many victims may have been targeted.

"This is a case with an enormous impact," she said.

"As a victim, you may not know what happened to you, because you may have been drugged and were unconscious.

"The news that your partner or an acquaintance may have drugged you and perhaps even raped you or attempted to do so can turn your life completely upside down." (BBC)

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