A 14-year-old boy from south London has been charged with an offence linked to extreme right-wing terrorism after a police search uncovered an alleged plot to target two mosques.

The boy was arrested on 9 July on suspicion of criminal damage to a vehicle. Officers dispatched to his address found “a number of documents of concern” during a search.

The Metropolitan Police said the terrorism charge relates to an alleged plan to target two mosques in the Sutton area of south London, noting that the affected mosques have been contacted and are being supported by specialist officers.

Following further enquiries by counter-terrorism police working with the Crown Prosecution Service, the boy was charged with preparation of terrorist acts on or before 9 July. He was also charged with racially aggravated damage to property by allegedly smashing a car window on or before 20 June, also in Sutton.

“This is a very serious terrorism charge against a young boy and likely to be highly concerning to the public and the local community.

“We know this will be particularly concerning to the Muslim community and we are working closely with the venues affected to ensure they are kept updated and to provide advice, support and reassurance, and this will continue,” said Helen Flanagan, the head of counter-terrorism policing in London.

Noting that it was deeply concerning to see someone so young charged with offences of this nature, Ms Flanagan expressed concern over the increasing number of children and young people appearing in police counter-terrorism casework.

The development came weeks after the Muslim Council of Britain advised mosques across the UK to carry out lockdown drills, strengthen ties with police and improve CCTV coverage amid growing concerns about anti-Muslim attacks.

The council warned that Muslim places of worship faced an increasing threat from vandalism, intimidation, threats and targeted hostility.