- Mamunur Roshid, 24, joined brutal terror group with his gang of extremists
- Ifthekar Jaman, 23, and Muhammad Rahman, 25, were also killed in past year
- Roshid part of group called the Britani Brigade Bangladeshi Bad Boys
- They flew to Turkey on bogus holiday before slipping over border to Syria
- Three dead young men all attended the same mosque in Portsmouth
- Met Commissioner says 100s of British extremists going to Syria each year
A third young Briton who travelled with friends to Syria to fight for Islamic State has been killed - and Britain's top police officer believes five British extremists a week are joining.
Mamunur Roshid, 24, joined the brutal terror group with his gang of extremists from Portsmouth, Hampshire, who pretended to go on a holiday to Turkey but then crossed into Syria.
His jihadist group also included Ifthekar Jaman, 23, and Primark worker Muhammad Hamidur Rahman, 25, who were also killed in Syria in the last 12 months.
Metropolitan Police Commissioner Sir Bernard Hogan-Howe today the fighting by British militants like these are 'not just the horrors of distant lands' and warned of the threat posed at home by returning fighters.
CCTV: Mamunur Roshid was one of five friends from Portsmouth who pretended to go on holiday but was in fact off to fight for Islamic State in Syria. They were caught on camera at Gatwick (pictured)
New death: Briton Manunur Roshid, 24, has died fighting with Islamic State in Syria. His friends Ifthekar Jaman, 23, , and Primark supervisor Muhammad Rahman, also died there in the past 12 months
He said: 'We know that over 500 British nationals travelled to join the conflict. Many have returned and many will wish to do so in the coming months and perhaps in future years.
'We still have an average of five people joining them a week. Five a week doesn't sound much but when you realise there are 50 weeks in a year, 250 more would be 50 per cent more than we think have gone already.
'Those numbers are a minimum. Those are the ones that we believe have gone. There may be many more who set out to travel to another country and meandered over to Syria and Iraq in a way that is not always possible to spot when you have failed states and leaky borders.'
Experts said today that Roshid may have been killed fighting for the town of Kobane, on Syria's border with Turkey, which has become the key target for ISIS fighters.
His family are in the dark about how he died, according to a community leader.
A total of ten young extremists from Portsmouth are believed to have left the south coast city for Syria and ISIS.
Warning: Metropolitan Police Commissioner Sir Bernard Hogan-Howe today the fighting by British militants like these are 'not just the horrors of distant lands'
Rashid was part of a group of five calling themselves the Britani Brigade Bangladeshi Bad Boys, the fanatics, all from Portsmouth, had been seduced by glamorous tales of martyrdom to join Islamic State – formerly Isis – establishing a Muslim caliphate in the Middle East.
CCTV showed them breezing through Gatwick Airport and looking like tourists setting off on a fortnight's holiday to Turkey.
In reality, the smiling Britons captured on CCTV were heading to Syria to fight their so-called 'holy war'.
As well as Roshid the group contained Muhammad Hamidur Rahman, 25, who is dead, Mashadur Choudhury, 31, who is in jail and Assad Uzzaman, 25,and Mehdi Hassan, 19, who are still fighting in Syria.
Ifthekar Jaman, 23, who was not on the Gatwick CCTV,
According to The International Centre for the Study of Radicalisation and Political Violence in London Roshid's death is the 25th confirmed British casualty have died in Syria.
Jaman, 23, was killed in a gun battle in December last year while Muhammad Hamidur Rahman, 25, died in August. A fourth man also from Portsmouth is also believed to be ill in hospital in Syria.
Jaman became known for his online advice and encouragement to fellow British Muslims seeking to go to Syria, including women, whom he urged to marry men back from the front lines.
The 23-year-old became one of the most infamous British extremists when he boasted on BBC Newsnight that the 'holy war' in Syria was like '5-star jihad' because of its 'relaxing' nature.
He also claimed it was 'cool' to hold a gun.
Place of worship: The men who fled for Syria attended the Jami Mosque in Portsmouth, pictured
Jaman (right) with his friend, former Primark supervisor Muhammad Hamidur Rahman, 25, (left) who was also from Portsmouth and was shot dead in July
PORTSMOUTH IN SHOCK AFTER ANOTHER ISIS DEATH HITS CITY
Confirming Roshid's death, Abdul Jalil, chairman of the city's Jami mosque, which all of the men attended, said today: 'The parents are very upset. I went to visit them and they told me that he had been killed in Syria. This is very difficult for them.
'We are very worried. They are on the front line.
'Five people went there and three have been killed.'
'It is a very big shock for their parents and we are working with the community to make sure that does not happen again.
'We are working with the police, the crime prevention team and the council to warn people, our youngsters especially, telling them not to go to Syria and also to get parents to watch their children.'
The Jami Mosque's treasurer - who would not give his name - said members were 'very sad' when they learned of Mr Roshid's death late on Sunday.
He said: 'It is very sad news, and we all feel it is very bad that these young men are going out to fight.
'We ask ourselves - why are they going there? It is not an Islamic war, it does not involve us.'
Roshid was killed on Friday and news of his death reached family members on Sunday.
A Foreign Office spokesman: 'We are aware of reports that a British national has been killed in Syria. The UK has advised for some time against all travel to Syria, where all UK consular services are suspended.
'As we do not have any representation in Syria, it is extremely difficult to get any confirmation of deaths or injuries and our options for supporting British nationals there are extremely limited.'
Sumel Chowdhury said the Muslim community did not support the views of the five men.
He said: 'In my view, they did not do a good thing. They did completely the wrong thing. We believe in peace, humanity and mankind.
'Islam does not say to kill people. It is completely unacceptable.'
Roshid was one of an estimated 500 Britons who have travelled to fight in Iraq and Syria, up to 30 of whom are believed to have died fighting.
Earlier this month four people were arrested for terrorism offences after the former home of Jaman, the ringleader of the group of five, was raided.
Jaman's mother and father, Enu Miah, 57, and Hena Choudhury, 48, were arrested and bailed, and his two brothers Tuhim, 26, and Mustakim, 23, were also arrested along with sister Tamannah Shaharin, 29.
Police stand guard outside the terrace house in Southsea, where Enu Miah, 57, and Hena Choudhury, 48, the parents of 23-year-old Ifthekar Jaman, were arrested in a dawn raid last week