A 50-year-old woman detained by Canadian immigration officials in a maximum-security prison in Milton, Ont., died on Monday, prompting more calls from critics for reform of the system.

She was detained at the Vanier Centre for Women by Canadian Border Services Agency (CBSA) — which has the power to arrest and jail foreign nationals under current immigration law.

She was "found in medical distress" at the facility and was "immediately taken to hospital," according to a CBSA news release.

She died "shortly thereafter," but the agency would not clarify if she died at, or on her way to, the hospital.

The Canada Border Services Agency says it is cooperating fully with an investigation into the death of a CBSA detainee in the Greater Toronto Area. (CBSA)

Derek Lawrence, communication adviser for the CBSA in the Greater Toronto Area Region, would not disclose the woman's identity, country of origin or her cause of death because an investigation has been launched.

The woman is the 10th person to die in immigration detention in Canada in the last five years and at least the 16th to die in the custody of the CBSA and its predecessor since 2000.

Ensuring accountability

Canada's immigration detention system has fallen under increased scrutiny this year, as a landmark legal challenge was launched to try to end the contentious practice of indefinitely jailing detainees.

Under current immigration law, detainees are not criminally charged, but can be detained indefinitely, either because they have been deemed a danger to the public, are unlikely to show up for their deportation or because their identity is in doubt.

On any given day in Canada, hundreds of people are detained under the Immigration and Refugee Protection Act. Last year the border agency detained 6,251 people, 32.6 per cent of which were held at non-CBSA facilities, such as provincial jails, even though they had not been charged with a crime.

Detainees are locked up an average of 19.5 days, according to CBSA statistics.

In Ontario, immigration detainees are held either at the Immigration Holding Centre, a minimum-security facility in Etobicoke exclusive to immigration detainees, or in maximum-security provincial jails. The woman is the eighth person to die in CBSA custody in the province since 2010.

Since 2000, at least 16 people have died in Canadian immigration detention centres. (Peter Macdiarmid/Getty Images)

Following a spate of hunger strikes at immigration detention centres last August, Public Safety Minister Ralph Goodale announced $138 million for a new national immigration detention framework aimed at creating a more humane system. Part of the money is being spent on upgrading the Toronto holding centre.

Coroner's juries have also criticized the border agency in the past for how it's dealt with detainees with medical needs — especially when it comes to providing medical authorities with proper health records.

In July, the federal government signed a contract with the Canadian Red Cross to monitor inmates being held at immigration detention centres to ensure the facilities comply with domestic and international standards.

The two-year contract stipulates that Canadian Red Cross must conduct regular visits throughout the year to detention facilities where immigration detainees are held.

Critics blast CBSA, blame deaths on current immigration laws

Despite all these recommendations, critics say crucial policy changes have yet to be made to the Immigration and Refugee Protection Act.

"People keep dying in immigration holding centres and maximum-security prisons," said Nisha Toomey, spokesperson for End Immigration Detention Network, a human rights organization.

"People will stop dying when the Canadian government stops leaving them there to die."

Toronto immigration consultant MacDonald Scott says the federal government has failed to address the challenges the current immigration system faces.

"The government is investing millions of dollars to expand and renovate immigration detention centres despite the inherent inhumanity of the entire system," said Scott.

"The latest death occurred because of Canadian laws and more will continue until these laws are changed."