A fourth person has been arrested in connection with the arson attack on Jewish volunteer ambulances in north-west London, the Metropolitan police has said.

The force said the 19-year-old man was arrested on Saturday morning at Westminster magistrates court, where three other men were charged over the arson attack.

“While attending the hearing of three other suspects, officers recognised the man as being involved in the arson attack. He was arrested for arson with intent to endanger life and taken into custody,” the Met said.

Hamza Iqbal, 20, and Rehan Khan, 19, both British nationals from Leyton, and a 17-year-old boy, a dual British and Pakistani national from Walthamstow, were charged with arson with intent to damage property and being reckless as to whether life would be endangered. They did not enter pleas and were remanded in custody during the hearing at Westminster magistrates court on Saturday.

The 19-year-old man was seen being taken out of the building, and the court was told that four suspects were involved in the alleged attack.

Four ambulances from Hatzola, a volunteer-led ambulance service operating in the Golders Green area, were set on fire in the early hours of 23 March, causing gas canisters stored in the vehicles to explode.

The fourth individual was arrested at the court on suspicion of arson with intent to endanger life and taken into custody.

The court was told that there was strong evidence to suggest the attack was a “premeditated and targeted attack against the Jewish community”.

Prosecution has now said that there is an investigation looking into whether an Iranian-backed group which is claiming responsibility was actually involved.

At court on Saturday morning, the three suspects were dressed in grey tracksuits and spoke only to confirm their names and addresses. Members of their families were present.

Counter-terrorism police are leading the investigation, but the incident “has not been declared as terrorism”, according to the Met police.

Cmdr Helen Flanagan, head of counter-terrorism policing London, which is leading the investigation, previously said: “Since this appalling attack last week, we have been working continuously to investigate and identify those responsible. The investigation has now reached a stage where three people have been charged and they will now appear in court.

“I want to reiterate that the support we had from the local community since this attack took place has been incredible, and we will continue to work closely with local policing colleagues to do everything we can to keep the public safe.”

Since the attack, police patrols have been set up in areas with large Jewish populations. Prime ​minister Keir Starmer described the incident at the time as a “deeply shocking antisemitic ⁠arson attack”.