The home secretary, Sajid Javid, has come under fire for his decision to revoke the British citizenship of Shamima Begum, whose baby son has died in a Syrian refugee camp.

Begum, 19, left the UK in 2015 with two school friends to join Islamic State in Syria and said last month she wanted to return home. But Javid insisted he would do all in his power to prevent her coming back and ordered her citizenship to be revoked.

Diane Abbott, the shadow home secretary, said the death of Begum’s baby, Jarrah, who was buried in a refugee camp on Friday, was a “stain on the conscience of this government”.

“It is against international law to make someone stateless,” she said. “And to leave a vulnerable young woman and an innocent child in a refugee camp, where we know infant mortality to be high, is morally reprehensible.”

Abbott called for Begum to be given the chance to have her actions fully investigated and – where appropriate – prosecuted, but said Javid had instead chosen to appease the rightwing press.

“What does it say about our government on International Women’s Day that it would allow hundreds of men to return to the UK from Syria and Iraq under similar circumstances, but strip citizenship from a young woman who was groomed as a minor?” she said on Friday. “It is clear that society is not past blaming groomed young women for their fate.”

The Conservative MP Phillip Lee said the decision was driven by populism. He told BBC Radio 4’s Today programme: “Clearly Shamima Begum holds abhorrent views and to want to join Islamic State is beyond all comprehension, but she was a child, a product of our society.

“I think we had a moral responsibility to her and indeed to her baby. That is why at the time I was just troubled by the decision. It seemed driven by a sort of populism, not any principle I recognise.”

A Kurdish intelligence official said Jarrah had been taken to hospital several times in the past week with breathing difficulties. A friend of Begum said “the baby turned blue and was cold” before being rushed to a clinic inside the camp. The infant is thought to have been buried along with two other children who were burned in a fire on Thursday night.

Begum was 15 when she travelled with two other schoolgirls to join the terror group in February 2015. She married the Dutch national Yago Riedijk, 27, soon after arriving in Syria. All three of their children are now confirmed to have died.

Play Video 2:44 UK citizenship decision is heartbreaking, says Shamima Begum – video

The heavily pregnant Begum spoke last month of her desire to return to the UK as the self-styled caliphate collapsed. Originally held in al-Hawl camp in northern Syria, she was transferred to al-Roj a week ago.

Brandon Lewis, the Conservative party chairman, defended Javid’s decision to strip Begum of her British citizenship. “The loss of any life of any child is absolutely tragic and is a very clear reminder – this whole case – of the danger of travelling out to that area and getting involved,” Lewis told Today. “The home secretary will have had advice and I know he made a decision based on what is in the national interest and the security of people here in the UK.

“There is no question that the duty of a home secretary in this country is to keep British people safe.”

After confirmation of the death on Friday night, a government spokesman said: “The death of any child is tragic and deeply distressing for the family. The Foreign and Commonwealth Office has consistently advised against travel to Syria since April 2011. The government will continue to do whatever we can to prevent people from being drawn into terrorism and travelling to dangerous conflict zones.”