Women were forced to sleep in temporary quarters at the Ottawa detention centre last Friday due to overcrowding after a police crackdown on prostitution, says a group that advocates for women in conflict with the law.

"There were beds set up ready to receive women in the doctor's office," said Bryonie Baxter, executive director of the Elizabeth Fry Society of Ottawa. "There were women literally on mattresses on the floor all over the place."

In addition, inmates were tripled up in cells designed to hold two people, Baxter said, because there were 66 women at the detention centre that day, even though it can comfortably house only 42.

Stuart McGetrick, a spokesman for the Ministry of Community Safety and Correctional Services, confirmed that the centre does have an official capacity of around 42 and the number of female inmates last Friday was "unusually high."

The overcrowding followed a downtown prostitution sweep by the Ottawa police, who reported last Tuesday they had arrested 20 women and charged them with 65 prostitution-related offences during the operation.

McGetrick said the detention centre has no control over the number of people sent there, but will transfer inmates to other facilities when it is overcrowded. However, that's only possible if the people housed there don't have a pending court appearance. If it is not possible to transfer inmates, they are still provided with bedding and mattresses.

"It's true that we do have to use the floor from time to time. It's not ideal," he said.

But he added that the spike seen last week is uncommon.

University of Ottawa criminology professor Christine Bruckert, who worked as a street-level prostitute for four years, said the police sweeps don't put much of a dent in the sex trade because most prostitutes work behind closed doors, but they do target the most vulnerable prostitutes.

"I think they're using it as a way of grandstanding," she said. "The issue is probably not about sex work but about satisfying community concerns."