The Security Services have reportedly identified the young man, who has not been named, as the leader the gang of more than 50 men who have waged a holy war against President Bashar al-Assad.
The man, who is his 20s and believed to be from a Bangladeshi family, is regarded as a high-ranking officer in an international group of terrorists devoted to bringing down the regime, the Times reported.
According to the paper, the man, who is from London, is believed to be a pious individual involved in military training for "raw" British recruits, who mostly live in the capital.
The jihadis, who said to have volunteered to the cause, include "hardened" Chechen fighters and crossed into Syria over the border from Iraq or Turkey.
The newspaper claimed that Scotland Yard had seized computers and mobile phones from addresses in Britain linked to the men with the material being "urgently" analysed.
Security chiefs estimate that there are just over 50 Britons in Syria fighting to bring down President Assad. A number of the group are believed to be Islamic fundamentalists, it added.
The gang are believed to be young Muslim males, mostly of Asian origin but with a number from North African backgrounds and some being white or Afro-Caribbean Islamic converts.
Authorities are particularly worried about the conflict because it is said to attract violent Muslim idealists who are likely to make contact with the global jihadi movement, the Times claimed.
They would return home having learnt how to use arms and explosives, posing a terrorist threat in Britain.
Security sources told the newspaper that authorities were concerned about the domestic threat emerging from Syria than they were about the conflict in Libya last year.
In comparison most of the "British fighters" who fought to overthrow Col Muammar Gaddafi were Libyan exiles.
Most of them live in the Manchester area and are said to be have been motivated by patriotism rather than an ideological jihad.
Scotland Yard has not commented on the claims.
