Hundreds of British teenage girls are still keen on joining Islamic State (Isis) despite the death of a London schoolgirl in Syria, according to counter-radicalisation experts, raising fresh doubts about the effectiveness of the government’s strategy to combat radicalism.

A significant number of young British women will not, they say, have been dissuaded from travelling to Syria following the killing of Kadiza Sultana during an airstrike on the city of Raqqa, the de facto Isis capital.

The 17-year-old left her home in Bethnal Green, east London, during the half-term break in February 2015 with her friends Shamima Begum and Amira Abase and is believed to have died during a Russian bombing raid.

Fiyaz Mughal, director of Faith Matters, which works on counter-radicalisation and community cohesion initiatives, said that, from the organisation’s interviews and first-hand experiences, a number of British teenage girls felt sufficiently disaffected with life in the UK that they preferred to live in the “calpihate”.

“We are looking at hundreds of young women who’d get up and go if they had the chance, as well as hundreds of men. What I am hearing and when I speak to people is that there is still a pool of young people who, if they had the means to go to Syria, would do so,” said Mughal. “But if you look at the 3 million Muslims in the UK, this is a tiny proportion.

“The only thing stopping them is the fear of getting caught; they’re frightened about how they can get there. They [the government] also know that there is a pool of individuals who want to go. Secondly, they are not only worried about young people going there but children born out there.”

Around 850 Britons have travelled to Syria to fight, according to the UK security services. Despite the difficulties in travelling and in entering the country, around 50 British nationals are believed to have successfully made it across the border into the war-torn country since January.

The warnings that other British teenagers remain keen to visit Syria, despite the death of Kadiza, have raised new disquiet over the government’s primary counter-terrorism strategy, Prevent, which urges parents, teachers and community leaders to share suspicions over “radicalised” behaviour.

Speaking in the wake of the news that Kadiza had been killed, the MP for Bethnal Green and Bow, Rushanara Ali, said that she had “huge concerns” over Prevent.

Days earlier, the parliamentary women and equalities committee had warned that Prevent was fuelling inequality and distrust in Muslim communities, which it said had the highest unemployment rate of any ethic group and also suffered from work discrimination and a lack of access to higher education.

“I find through our work that some of the biggest cheerleaders [for Isis] are women and it’s women who are often feeling the most marginalised, saying ‘I don’t feel that my future’s in the UK’. This message seeps into the minds of young people. Also, the Bethnal Green schoolgirls have inspired a lot of their peers,” added Mughal.

Concern over the effectiveness of the government’s approach to neutralise the appeal of Isis is expected to be articulated in the government’s forthcoming review into improving the integration of Britain’s minorities, as part of a broader effort to tackle extremism. The review, headed by Louise Casey, will look at the issue of radicalisation and extremism within communities most separated from the mainstream.

“The government needs to engage and speak to communities, get their integration strategy sorted out and how that links in with extremism. At the moment they have adopted a securitisation approach that’s causing a lot of anger and resentment,” said Mughal.

Within the “caliphate”, the death of Kadiza promises ramifications for her two friends who remain in Raqqa. Reports have suggested that the east London trio enjoyed a relative degree of independence inside the city, which is estimated to have a population of between 250,000 and 500,000.

Their families have reportedly been told that their daughters were free to visit the city’s internet cafes without being in the company of a man. Yet details that Kadiza had become disillusioned with life in Raqqa and was hatching plans to escape to Britain may now compromise her friends, who risk being placed under tight surveillance.

Conditions for the remaining two London schoolgirls potentially deteriorated several days ago when fresh Russian air strikes on Raqqa cut the city’s water supply after a water pumping station was hit.

Isis, aware of the propaganda value of the Bethnal Green schoolgirls, will be keen to ensure the remaining teenagers do not escape. Last November Austrian Isis poster girl, Samra Kesinovic, 17, was murdered by Isis militants during a failed attempt to flee.