The brother of two British teenagers who were killed fighting for Islamists in Syria has been knifed to death following a car crash in Brighton.

Abdul Deghayes, 22, was found with multiple stab wounds in the passenger seat of a Volkswagen Polo which smashed into a number vehicles on Saturday night.

Sussex Police has launched a murder investigation and said it was ”trying to establish the exact circumstances of what has led to this young man’s tragic death”.

Mr Deghayes’s twin brother, Abdullah, died aged 18 in 2014 while fighting for al-Nusra Front, a jihadi group which was battling to overthrow the Syrian government. Months later their younger brother, Jaffar, 17, was shot dead by president Bashar al-Assad’s troops.

Their elder brother, Amer, 28, also travelled to Syria to fight alongside jihadis and is believed to still be alive.

Conflict in Syria creates wave of British jihadists Show all 2 1 /2 Conflict in Syria creates wave of British jihadists Conflict in Syria creates wave of British jihadists web-syria-getty.jpg The Syrian rebels are drawing recruits from a variety of national backgrounds Getty Images Conflict in Syria creates wave of British jihadists web-syria-2-epa.jpg Russia’s Foreign Minister Sergei Lavrov met William Hague in London yesterday EPA

Police said Adbul was found stabbed in the Volkswagen at 9.30pm in Elm Grove. He taken to Royal Sussex County Hospital, where he was pronounced dead just before 6.30am on Sunday.

Chief Inspector Andy Bennett said: “We are aware that the car was in collision with other vehicles shortly before he was found to have suffered these injuries, which we are satisfied were caused maliciously and not as a result of the collision.

“Our thoughts are with Abdul’s family and friends at this tragic time and we have specialist family liaison officers supporting them.”

Police appealed for witnesses and said the area where Abdul was found “would have been very busy” on Saturday night.

Abdul was jailed for drug dealing in 2017, when his lawer highlighted the psychological impact of losing his brothers at a young age.

"The trauma of that loss has made its mark," Charles Macdonald told Hove Crown Court, according to a report in The Argus.

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A serious case review published the same year criticised child safeguarding teams for failing to stop the radicalisation of Abdul's brothers despite monitoring them for years.

Brighton and Hove Local Safeguarding Children Board found there had been “no recognition” that the siblings were beoming vulnerable to radicalisation and exploitation.

The review added authorities had little understanding of the part religion played in the lives of Abdullah and Jaffar, who were both killed within moves of travelling to Syria in 2014

Their family, who moved to the UK after fleeing Muammar Gaddafi’s regime in Libya, had been known to local authorities in Brighton for decades over domestic abuse and as the victims of racist attacks.