Ebrahim Raisi says he has contacted Kurdish woman’s family but laments western double standards on human rights.

The death in custody in Iran of a Kurdish woman that has sparked widespread protests must be “steadfastly” investigated, Iran’s president has said, even as he lamented what he claimed were western “double standards” on human rights.

Ebrahim Raisi told a news conference on the sidelines of the UN general assembly in New York that the death of Mahsa Amini while in the custody of Iran’s morality police “must certainly be investigated”.

At least 36 people are feared by rights groups to have died in six days of protests, sparked by the death on 16 September of the 22-year-old Kurdish woman.

Raisi, a former hardline head of the judiciary accused of sending hundreds to their death in the past, said Iran would not tolerate “acts of chaos”, referring to the six nights of protests over her killing, but said his country accepted lawful protest.

The US imposed sanctions on the morality police and leaders of other Iranian security agencies on Thursday, saying they “routinely employ violence to suppress peaceful protesters”.

Nasser Kanani, the spokesperson of the Ministry of Foreign Affairs of the Islamic Republic, wrote in a tweet without referring to the nationwide protests in Iran: “The real violators of human rights do not have the necessary moral competence to comment on human rights.”

The protests have no organised leadership and although the focus initially has been on the right of women not to wear the hijab in public or be harassed by the morality police, there have been broader calls for freedom, or overthrow of the regime

US-based human rights groups had been trying to serve a writ on Raisi on behalf of former political prisoners including Kylie Moore-Gilbert, the British-Australian dual national kept in jail for two years