An Iranian coroner's report has denied Mahsa Amini had died due to blows to the head and limbs while in the custody of Iran's morality police and linked her death to pre-existing medical conditions, state media said.

The death of the 22-year-old while in police custody has ignited three weeks of nationwide unrest, marking the biggest challenge to Iran's clerical leaders in years.

Her father has said she suffered bruises to her legs, and has held the police responsible for her death.

The coroner's report said her death was "not caused by any blow to the head and limbs." It did not say whether she had suffered any injuries.

Ms Amini was arrested in Tehran on 13 September for "inappropriate attire", and died three days later.

Rights groups say more than 150 people have been killed, hundreds injured and thousands arrested by security forces confronting protests which erupted after her death, prompting condemnation from the United States and its allies.

Washington said it would continue to coordinate its response with its allies and partners, and Canada said it was expanding sanctions on groups related to Iran's elite Revolutionary Guards force, calling it a terrorist organisation.

France urged all its nationals to leave Iran as soon as possible, citing a risk of arbitrary detention. The Dutch government also urged all Dutch nationals to leave Iran and advised against all travel to the country, Dutch news agency ANP quoted the foreign minister as saying.

Referring to the day Ms Amini collapsed in custody, the coroner said she had briefly regained consciousness but that "cardio-respiratory resuscitation was ineffective in the first critical minute, resulting in brain damage."

The report noted pre-existing medical conditions linked to a brain tumour for which she had undergone an operation when she was eight years old. "She died due to multiple organ failure caused by cerebral hypoxia," it said.

The police, who have enforced strict dress codes since Iran's 1979 Islamic Revolution, have denied she suffered any harm, previously saying she suffered a heart attack.

Her family deny she had any heart problems.

The government has ordered an investigation into her death.

During the nationwide protests demonstrators have damaged symbols of the Islamic Republic and called for the downfall of Supreme Leader Ayatollah Ali Khamenei.

Human rights group Hengaw posted a video yesterday that it said showed drivers blowing their car horns in protests on the streets of Saqez, Ms Amini's home town.

The government has described the protests as a plot by Iran's enemies including the United States, accusing armed dissidents - among others - of violence in which at least 20 members of the security forces have been reported killed.

State TV broadcast a mass funeral in Tehran yesterday for a member of the Basij, a volunteer militia deployed to quell unrest, saying he had been stabbed by protesters.

Iran summoned the Danish ambassador to protest an incident at its embassy in Copenhagen in which its ambassador was threatened, Iran's foreign ministry said. Danish police earlier said they had arrested a 32-year-old Iranian man after he entered the grounds of the embassy carrying a knife.

Analysts do not believe the clerical establishment is close to being toppled despite growing frustration over strict social and political limitations imposed over the past four decades since the fall of the US-backed Shah.

Women have played a prominent role in the protests, waving and burning headscarves. Secondary school girls have also taken part.