The Kurdish-populated provinces of western and northwestern Iran have been major hubs from protest since the onset of the movement sparked by the death in September of Mahsa Amini, 22, who had been arrested by the Tehran morality police and was herself Kurdish and from the area.

There have been particularly intense anti-regime demonstrations in several towns in the last few days, largely sparked by the funerals of people said to have been killed by the security forces in previous protests.

The Norway based Hengaw rights group said Iranian forces had shelled overnight the cities of Piranshahr, Marivan and Javanroud, posting videos with the thud of heavy weaponry and sound of live gunfire.

It said at least two people had been shot dead by security forces in Javanroud while a 16-year-old teenager was killed in Piranshahr. Hengaw posted videos of their funerals being held Monday.

The latest violence came amid continued concern over the situation in Mahabad, where rights groups said security forces had sent reinforcements the day earlier to press a crackdown.

"Greatly concerned that Iranian authorities are reportedly escalating violence against protesters, particularly in the city of Mahabad," US Secretary of State Antony Blinken wrote on Twitter.

"We continue to pursue accountability for those involved, as we support the Iranian people," he added.

The Norway-based Iran Human Rights (IHR) group also posted footage it said showed security forces using live fire against protesters in Piranshahr, and of the distraught mother of the 16-year-old killed prostrating herself on his corpse as it was taken for burial.

"Mother, don't cry, we will take revenge," the mourners chanted in Kurdish, the group said.

People also took to the streets in Kermanshah, a Kurdish-populated provincial capital, chanting "death to (supreme leader Ayatollah Ali) Khamenei", another video posted by IHR said.

Kurds make up one of Iran's most important non-Persian ethnic minority groups and generally adhere to Sunni Islam rather than the Shiism dominant in the country.

In a related development, Iran launched new cross-border missile and drone strikes overnight to Monday in neighbouring Iraq against Kurdish opposition groups it accused of stoking the protests.

The latest Iranian attacks also come a day after Turkey carried out air raids against outlawed Kurdish militants in Iraqi Kurdistan and northern Syria.