A Romanian man has appeared at Derry Magistrates' Court on a prostitution charge.
25 year-old Razan Nocolae Gros of Kular Court in the city's William Street was charged with controlling the activities of a Romanian woman for the purposes of prostitution.
Mr Gros, who police suspect is also active in prostitution in the Donegal, was further charged with obtaining an improper Romanian driving licence and identity card.
An officer in the PSNI's organised crime branch said that during a search of a flat on Monday the defendant and a Romanian woman whom the defendant said was his girlfriend were inside the property.
Items associated with prostitution had been found in the flat.
The police witness said officers seized eight mobile phones, a sum of money and 12 sim cards for use in Northern Ireland and the Republic.
Several of the sim cards were marked with female names, which police believe to be the names of prostitutes operating on both sides of the Irish border in Donegal and Derry.
The officer said that during the interview, the defendant denied that the Romanian woman in his flat was a prostitute and that the flat was being used for the purposes of prostitution.
However, he said that several friends would visit the flat for 10 to 15 minutes.
The officer said one of the mobile phones was examined by a forensic officer who found links which he believed related to six prostitutes who advertised online.
The officer said the defendant's fingerprints were taken and shared with gardai.
Mr Gros was remanded in custody.