Head of Britain’s domestic spy agency MI5 has warned that terrorist threats against the UK are substantial citing \"thousands of Islamic extremists\" who see British people as a legitimate target. \"Al Qaida and its affiliates in South Asia and the Arabian Peninsula present the most direct and immediate threats to the UK,\" Andrew Parker said Wednesday in his first public remarks since being appointed as the MI5 chief in April. He said that Syria was a growing concern for British security services, and the number of cases regarding Syria was growing as more people from the UK travelled to fight there and a number of arrests have been made this year. \"Al Nusra and other extremist Sunni groups there aligned with Al Qaeda aspire to attack Western countries,\" Parker warned. Parker reminded of terrorist attacks which had been conducted by British nationals on UK soil. He, however, pointed out that he did not think the threat level now was worse than before. He said that there was an increase in smaller-scale attacks and threats from \"groups and individuals taking it upon themselves to commit acts of terrorism\". Amandla Thomas-Johnson from the London-based human rights watchdog Cageprisoners described as \"absurd\" the top spy’s assertion that British nationals returning from fighting in Syria were a threat to the UK. \"People that go and fight in Syria do so because they wish to remove an unjust ruler, people that attack the UK [do so] because of British foreign policy. There is no empirical evidence to suggest that British nationals fighting in Syria pose a threat to the UK,\" Thomas-Johnson said. According to Cagedprisoners, the overwhelming majority of individuals going to Syria are traveling there to help humanitarian efforts.