More than 75 people have been killed in the Iranian authorities' crackdown against unrest sparked by the death of Kurdish woman Mahsa Amini in morality police custody, a rights group said Monday.

The Iranian authorities' official death count, meanwhile, remained at 41, including several members of the security forces.

Officials said Monday they arrested more than 1,200 people as the dragnet widens against the nationwide demonstrations over Amini's death following her arrest for allegedly breaching the country's strict rules on hijab headscarves and modest clothing.

Protesters took to the streets again on Monday night -- as they have every night since Amini's death on September 16 -- in Tehran and elsewhere, witnesses told AFP.

Tehran crowds shouted "death to the dictator", calling for the end of the more than three-decade rule of supreme leader Ayatollah Ali Khamenei, 83.

Video shot from several floors above street level, purportedly in the city of Tabriz, showed people protesting to the sound of tear gas canisters being fired by security forces, in images published by Oslo-based group Iran Human Rights (IHR).

IHR said at least 76 people have been killed in the crackdown in Iran, up from a previous count of 57.

Women in Sanandaj, Kurdistan province, twirled their headscarves above their heads in defiance while car drivers sounded their horns in solidarity, in video shared by Hengaw, a Kurdish rights organisation likewise based in Norway.

Tensions with Western powers grew as Germany summoned the Iranian ambassador and Canada announced sanctions, a day after the European Union deplored the crackdown and Tehran called in the British and Norwegian envoys.

'Police On Duty 24 Hours'

"We call on the international community to decisively and unitedly take practical steps to stop the killing and torture of protesters," said IHR's director Mahmood Amiry-Moghaddam.

Video footage and death certificates obtained by IHR showed that "live ammunition is being directly fired at protesters," he alleged.

Iranian riot police in black body armour have beaten protesters with truncheons in running street battles, and students have torn down large pictures of the supreme leader and his predecessor Ayatollah Ruhollah Khomeini, in recent video footage published by AFP.

Amnesty International on Monday reported that Hadis Najafi, a 22-year-old protester, was killed on September 21 in Karaj. "Security forces fired birdshot at her in close range, hitting her in the face, neck and chest," the rights group said, corroborating earlier social media versions of events.

Protesters have hurled rocks, torched police cars and set public buildings ablaze.

Authorities say about 450 people have been arrested in northern Mazandaran province, on top of over 700 reported Saturday in neighbouring Gilan, along with dozens in several other regions.

Twenty journalists are among those arrested, according to the Committee to Protect Journalists.

"Rioters have attacked government buildings and damaged public property," Mazandaran's chief prosecutor Mohammad Karimi told official news agency IRNA, charging that they were steered by "foreign anti-revolutionary agents".

Tehran police have been deployed "24 hours a day" and many have not slept, said the Iranian judiciary chief, Gholamhossein Mohseni Ejei, thanking exhausted officers and the capital's police chief during a visit to their headquarters Sunday, in a video posted by Mizan Online.

Ejei earlier stressed "the need for decisive action without leniency" against the protest instigators.

But a powerful Shiite cleric long aligned with the country's ultra-conservative establishment urged authorities to take a softer line.

"The leaders must listen to the demands of the people, resolve their problems and show sensitivity to their rights," said Grand Ayatollah Hossein Nouri Hamedani on Sunday.

Tensions With West

Despite sweeping internet restrictions, including blocks on Instagram and WhatsApp, new videos shared widely on social media showed protests Sunday night in Tehran and cities including Yazd, Isfahan and Bushehr on the Persian Gulf.

Reports said that students at Tehran and Al-Zahra Universities and the Sharif Institute have gone on strike and urged professors to join them.

The EU's foreign policy chief Josep Borrell on Sunday slammed Iran for its "widespread and disproportionate use of force against nonviolent protestors".

He said the EU would "continue to consider all the options at its disposal ... to address the killing of Mahsa Amini" and the state response to the protests in Iran, a country already under punishing sanctions over its nuclear programme.

Tehran, for its part, said Sunday it had summoned Britain's ambassador to protest what it called an "invitation to riots" by London-based Farsi language media, and Norway's envoy over the parliamentary speaker's "unconstructive comments" on the protests.

The United States last week imposed sanctions against the morality police, and Canadian Prime Minister Justin Trudeau said on Monday that his own country would follow suit as part of a sanctions package "on dozens of individuals and entities".