Iran on Wednesday hanged a woman convicted of murdering her husband, whom she married while still a child, a human rights group said, defying an international campaign for clemency.

Samira Sabzian, who had been in prison for the past decade, was executed at dawn in Ghezel Hesar prison in the Tehran satellite city of Karaj, the Norway-based Iran Human Rights (IHR) group said.

It said she was a "child bride" who had married her husband at the age of 15 and had been a victim of domestic violence, according to relatives.

She was arrested 10 years ago when she was aged 19 on charges of murdering her husband and then subsequently sentenced to death, it said.

She had two children who she had not seen after her arrest until a final meeting in prison earlier this month, IHR said.

"Samira was a victim of years of gender apartheid, child marriage and domestic violence, and today she fell victim to the incompetent and corrupt regime's killing machine," said IHR director Mahmood-Amiry Moghaddam.

Rights groups have raised alarm over a surge in executions in Iran this year, with at least 115 people put to death in November alone according to Amnesty International.

Amnesty had urged Iran not to carry out the execution, saying the authorities were implementing a "horrific state-sanctioned killing spree".

The British government had called on Iran to spare Sabzian's life.

"Samira is a victim of child marriage… Iran must cease its appalling treatment of women and girls," junior foreign minister Tariq Ahmad said on X, formerly Twitter, late Tuesday.

According to IHR, 18 women have now been executed in Iran this year, including Samira Sabzian.