The four men were identified as being of Portuguese and foreign nationality and live in Switzerland, while the two victims are British girls.
A statement from the PJ explained the men were on holiday in Portugal when they met the two female victims, aged 20 and 23, who were also holidaying in Lisbon.
After going out a couple of times to the city’s bars and discos together, the alleged perpetrators lured the victims back to an apartment where the men were staying and, “in a highly constrained environment”, raped one of the girls.
According to the statement the men also took advantage of the heavily drunken state of the other victim to have sex with her.
The suspects will be held in custody pending trial.