A new United Nations report criticizes the Iranian government for its continued crackdown on freedom of expression and restrictions on access to information, while detainees appeared to be systematically subjected to abuse, including torture and rape.

The report published on March 5 was drafted by Asma Jahangir, a Pakistani human rights activist and lawyer serving as UN special rapporteur on human rights in Iran, who died last month.

In the report, Jahangir wrote that she had seen "a worrying picture developing in the human rights situation" in the country since her previous report in August.

"Despite assurances from the government, improvements are either not forthcoming or are being implemented very slowly and in piecemeal," she added.

There were no immediate comments from Iranian officials.

The report is set to be debated before the UN Human Rights Council next week.

Jahangir said she remained "alarmed" by the "consistently reported pattern of serious violations of the right to fair trial and denial of due process" in the country, citing arbitrary detentions and the use of torture and other ill-treatment particularly in prisons.

"Consistent reports received suggest a pattern of physical or mental pressure applied upon prisoners to coerce confessions, some of which are broadcast," the UN expert said.

The special rapporteur was never allowed to visit Iran, but she said she had met with at least six people in recent months who had fled the country and "who still bore marks of torture" suffered in detention.

Jahangir pointed to recent findings by the Freedom from Torture organization of widespread torture during interrogations of detainees, including rape and other sexual violence, electric shocks, and amputations.

She raised "grave concern [over] a pattern of denial of medical treatment to certain categories of detainees, especially prisoners of conscience, political prisoners, and human rights defenders."

She also called for a halt in executions, flogging, and amputations.

The reports said 482 executions were reported in the country in 2017, including five juvenile offenders, down from 530 in 2016 and 969 in 2015.

Jahangir also urged Tehran to halt the use of harsh corporal punishment, saying 50 flogging sentences and five amputation sentences were reportedly carried out in the country last year.

Meanwhile, new restrictions have been placed on freedom of expression, association, and peaceful assembly, and access to information, the report said.

Pro-democracy activists, especially those with dual nationality, have been targeted for arrest, amid reports of at least 30 dual nationals being imprisoned since 2015, it said.

Jahangir called for freedom of the press and online access, saying the government had closed 7 million Internet addresses over the past three years.

Journalists and Internet users have been arrested and the families of people working for the Persian service of the BBC told Jahangir that their relatives in Iran were harassed, the UN expert said.

Meanwhile women, religious and ethnic minorities, and lesbian, gay, bisexual, and transgender (LGBT) people were subject to discrimination.

With reporting by Reuters and AFP