The infant son of Shamima Begum, a British-born teenager who left London to join the Islamic State in Syria, has died, Reuters quoted a spokesperson of the Syrian Democratic Forces as saying on Friday. The 19-year-old, who left her home country in 2015 to join the terror group, was stripped of her British citizenship last month on security grounds.

Begum had married Yago Riedijk, a Dutch fighter for the Islamic State who surrendered to Syrian fighters. A British journalist, who came across a pregnant Begum living in a refugee centre in northeastern Syria, was told that she wanted to return home. The baby, born about three weeks ago in the camp, was named Jarrah.

Syrian Democratic Forces spokesperson Mustafa Bali on Friday confirmed that the child has died. The baby’s medical certificate showed that he died of pneumonia, the BBC reported. Riedijk, who is being held at a nearby prison, has been informed about the death.

A paramedic working for the Kurdish Red Crescent in the camp said the baby had been suffering from breathing difficulties. He was taken to a doctor on Thursday morning before being shifted to a hospital, along with his mother. He died at 1.30 pm local time, 5 pm India time, on Thursday and was buried at the camp.

Begum’s family’s lawyer on Friday also confirmed the baby’s death. The teenager had previously given birth to two other children, who are said to have died from illness and malnutrition.

A British government spokesperson said the death was “tragic and deeply distressing”.

“The Foreign and Commonwealth Office has consistently advised against travel to Syria since April 2011,” it said in a statement. “The government will continue to do whatever we can to prevent people from being drawn into terrorism and travelling to dangerous conflict zones.”

Home Secretary Sajid Javid had earlier said he “would not hesitate” to prevent the return of those who joined terror organisations like the Islamic State.

Following news of the boy’s death, Shadow Home Secretary Diane Abbott criticised Javid’s decision. “It is against international law to make someone stateless, and now an innocent child has died as a result of a British woman being stripped of her citizenship,” she said in a tweet. “This is callous and inhumane.”