More than 150 British militants who went to Syria to join Isil have been stripped of their citizenship and banned from returning to the UK.

This year alone has seen more than 40 terrorism suspects stripped of their right to a British passport, as security officials fear an influx of militants could return from Syria as in the event of the collapse of Isil.

The terror group has been losing ground Syria, where its grip on Raqqa appears to be loosening, and security intelligence have warned ministers that 300 fighters could return to Britain to commit acts of terror.

At least 850 British citizens have travelled to the region, it has been reported. Of those half have returned while 150 have been killed.

According to The Sunday Times, ministers have stepped up efforts to issue deprivation orders since the Manchester and London terror attacks: 30 have been issued since March

Among those stripped of their citizenships are so-called “jihadi brides” who went the region to marry fighters and live under Isil’s caliphate.

All of those subject to the deprivation orders are Britons with dual nationality, as ministers are not able to take away citizenship if it leaves a suspect “stateless”.

There are concerns that Britain is ill-prepared for the collapse of Isil’s caliphate and the impact it will have on home soil.

Security minister Ben Wallace told the Sunday Times: “We have planned and prepared for the risk posed by British returnees as Daesh [Isil] is defeated in Iraq and Syria, and are using a range of tools to disrupt and diminish that threat.”

Anti-terror laws in Britain will be reviewed in the autumn amid calls that suspects should be subject to tighter controls in the UK.