A Human Rights Watch report has detailed the damning state of immigration detention centres in Malaysia that house thousands of refugees and asylum seekers, listing claims of human rights violations and abuse.

The Malaysian government is detaining about 12,000 migrants and refugees, including 1,400 children, in conditions that put them at serious risk of physical abuse and psychological harm, HRW said in the report released yesterday.

The 60-page report, "We Can't See the Sun: Malaysia's Arbitrary Detention of Migrants and Refugees", documents Malaysian authorities' punitive and abusive treatment of migrants and refugees in 20 immigration detention centres across the country.

Immigration detainees can spend months or years in overcrowded, unhygienic conditions, subject to harassment and violence by guards, without domestic or international monitoring.

"Malaysian authorities are treating migrants as criminals, arbitrarily holding them for prolonged periods in immigration centres with almost no access to the outside world," said Shayna Bauchner, Asia researcher at HRW.

Malaysia's degrading and abusive immigration detention system denies migrants and refugees rights to liberty, health and due process, she said.

HRW interviewed more than 40 people, including former immigration detainees, family members, lawyers, humanitarian aid staff and former immigration officials, for the report.

Malaysian law makes all irregular entry and stays in the country a criminal offence, with no distinction among refugees, asylum seekers, trafficking victims and undocumented migrants.

There is also no legal limit on the length of immigration detention, leaving migrants at risk of being detained indefinitely. Authorities have detained more than 45,000 irregular migrants since May 2020.

Former detainees described a bare and brutal existence inside the immigration detention centres, also called depots, with limited food and hygiene supplies, frequent water shortages, strict and unpredictable rules and the ever-present threat of punishment.

"We would get beaten when we asked for more food, took an extra mug of water to shower or asked for a blanket for the cold," said a Rohingya refugee previously detained at the Belantik immigration depot.

"If we made any noise, we would be punished, like hanging from the wall, pushups, squats, walking like ducks, or standing under the hot sun for hours," said an Indonesian woman held in the Tawau immigration depot.

The Malaysian government has denied the United Nations refugee agency UNHCR access to immigration detention centres since August 2019, leaving the organisation unable to review asylum claims or protect detainees registered as refugees.

Malaysia has also not ratified the Refugee Convention, the HRW report said.

Children detained in the immigration centres face the same abuses as adult detainees, including denial of medical care, inadequate food and ill-treatment. Malnutrition is widespread, the report said.

The Malaysian government's immigration detention of children contravenes international law, HRW said, while calling upon the country to reduce reliance on immigration detention and move toward abolishing it entirely.

"Malaysia should seriously consider adopting measures used by other countries that better manage immigration objectives," Bauchner said.