The Toronto police force, which is already under intense public scrutiny, is facing fresh questions after it emerged that three off-duty officers on vacation in Barcelona were arrested in connection with a sexual assault last week.

According to police in Barcelona, the alleged assault occurred in the early hours of 13 May, when the trio of police officers were travelling in a taxi with a sex worker in the Ciutat Vella neighbourhood of the Catalan capital.

The officers allegedly tried to force the woman to have sex with them all simultaneously, according to the regional paper El Periódico de Catalunya. When she refused, the three suspects are alleged to have become violent and to have started insulting, threatening and beating the woman.

“One of the officers in the back allegedly sexually assaulted the victim, while the other allegedly punched her in the face, causing a cut above her eyebrow that required stitches due to profuse bleeding,” the newspaper wrote. “Faced with this situation, the woman called for help from the taxi window.”

When plainclothes officers from Barcelona’s municipal police force stopped the taxi and ordered its occupants out, one of the Canadian policemen allegedly reacted violently, while another – who had allegedly hit the woman – ran away.

Two of them were arrested at the time, while a third fled,” said a spokesperson for the Catalan police, the Mossos d’Esquadra. “One of the two men arrested in Barcelona has been charged with sexual assault and assault, while another has been released on bail. The third man was arrested on the morning of Friday 15 May in Palma de Mallorca in cooperation with the Guardia Civil.”

It was the local media reports in Barcelona that first tipped off Canadian media that the officers had been arrested and faced criminal charges. The Toronto police service confirmed the arrests on 18 May, but it did not respond to questions over why it failed to proactively disclose the arrests by Catalan police.

A Toronto police spokesperson called the allegations “serious” but said the force was not identifying the officers. The police service said it was unable to comment further on the charges, as the matters are now before the court.

The allegations come as the police force, the largest in Canada, grapples with immense reputational damage over recent allegations of corruption.

In recent months, at least eight officers have been charged in a sprawling investigation for accepting for bribes, aiding drug traffickers, leaking personal information to criminals who then carried out shootings, and helped members of organised crime in a plot to murder a corrections officer. The investigation, Project South, has exposed the “corrosive” reach of organised crime into Canada’s largest municipal police service, said the city’s police chief.

None of the officers arrested in Spain has been linked publicly to Project South.

The Toronto police association, which represents police officers, said it was aware of the incident involving three of its members but provided no further details.

“Given these charges relate to an off-duty incident, the Toronto police association has no further comment,” the group said.