U.S. attempts to violate Iran's sovereignty over the issue of protests triggered by the death of a woman in police custody will not go unanswered, the foreign ministry said on Monday, as the biggest unrest since 2019 showed no signs of abating.

Iran has been rocked by nationwide demonstrations sparked by the death of 22-year-old Kurdish woman Mahsa Amini, after she was detained by morality police enforcing the Islamic Republic's strict restrictions on women's dress.

The case has drawn international condemnation. Iran said the United States was supporting rioters and seeking to destablise the Islamic Republic.

"Washington is always trying to weaken Iran’s stability and security although it has been unsuccessful," Iran's Foreign Ministry spokesperson Nasser Kanaani told Nour news, which is affiliated with a top security body, in a statement.

On his Instagram page, Kanaani accused the leaders of the United States and some European countries of abusing a tragic incident in support of the "rioters" and ignoring "the presence of millions of people in the streets and squares of the country in support of the system."

The anti-government protests are the largest to sweep the country since demonstrations over fuel prices in 2019, when Reuters reported 1,500 people were killed in a crackdown on protesters - the bloodiest bout of internal unrest in the Islamic Republic's history.

The state has organised demonstrations in an attempt to defuse the crisis.

Iran has blamed armed Iranian Kurdish dissidents of involvement in ongoing unrest in the country, particularly in the northwest where most of Iran's up to 10 million Kurds live.

Iran's Revolutionary Guards launched a new artillery and drone attack on Iranian militant opposition bases in the Kurdish region of northern Iraq, the semi-official Tasnim news agency reported.

A main Iranian teachers union, in a statement posted on social media on Sunday, called for teachers and students to stage the first national strike since the unrest began, on Monday and Wednesday.

Reuters