Muhammad Hamidur Rahman, 25, from Portsmouth thought to be one of about 500 Britons fighting for the Islamic State

A former supervisor at Primark who left the UK to fight in Syria has been killed, it has been reported.

Muhammad Hamidur Rahman, 25, from Portsmouth is thought to be one of about 500 Britons who have travelled to Syria to fight for the Islamic State (Isis) and other jihadi groups.

On Sunday his father, Abdul Hannan, 52, told the Daily Mail the family received a text from a friend of Rahman in Syria who told them their son had been shot dead in a gun fight a fortnight ago. Rahman's father said his son had travelled to Syria in October but had not told any member of his family that he was going. Days later, they received a call from him saying he was in Syria.

Hannan said: "He asked us to pray for him, and said he wanted to become a shaheed [martyr] for the sake of Allah.'

Shiraz Maher, a terrorism expert at the International Centre for the Study of Radicalisation (ICSR) at King's College, London, which monitors the war in Syria told the Daily Mail he had spoken to Rahman on social media a month ago, when he said he was in the northern Syria city of Deir Zour, which is a stronghold for IS [the new name for Isis].

Maher said: "From speaking to him, I got the sense that he was a man who wanted to become a martyr. He was a man of conviction."

Rahman, who was reportedly dismissed from his local Primark store before he left for Syria, is thought to be one of at least eight Britons from Portsmouth who have travelled to the middle east to join the fighting. The men allegedly decided to go to training camps after another associate, Iftekhar Jaman, 29, had travelled to fight with Isis earlier last year. He was killed in December , shortly after he had given an interview to BBC Newsnight.

In May, Mashudur Choudhury, 31, who accompanied Rahman, but returned to the UK, became the first person in the UK to be convicted of taking part in terrorist activity in Syria. He was arrested in October at Gatwick airport by anti-terrorist police, as he flew back from Turkey.