A memorial wall in Golders Green, north London, has been targeted in a suspected arson attack.
The Metropolitan Police said it received reports of a fire at the site in Limes Avenue on Monday, but the wall itself was not damaged.
Counter Terrorism Policing is leading the investigation – but the incident is not being treated as terrorism, the force said.
The incident follows another alleged arson attack that saw four Jewish community ambulances destroyed in Golders Green in late March.
The memorial wall is a tribute to thousands of protesters killed in a crackdown in Iran in January and is near a Jewish centre.
Police said the suspected arson attack took place at around 12.15am on Monday, and was reported later that day just before 7.30pm.
Detective Chief Superintendent Luke Williams said: “We recognise that this incident will heighten concerns in the Golders Green area, where residents have already faced a series of attacks.
“We are working closely with community organisations and leaders, and want to reassure them that our protective security operation continues.
“Our local officers are working closely with Counter Terrorism Policing to support their investigation.
“Since last month’s attack in Golders Green, we have stepped up our work to reassure communities.
“This includes armed police patrols as well as deployments of officers from Project Servator, who are specially trained to spot anyone who may be planning or preparing to commit criminal acts.”
A group calling itself Harakat Ashab al-Yamin al-Islamia, the Islamic Movement of the Companions of the Right (Hayi), has claimed responsibility for the series of arson attacks on Jewish sites in north London, as well as an incident where drones were flown near the Israeli embassy.
Two men arrested under terrorism laws over the bizarre incident have now been released from police custody, the Met said.
A 39-year-old man who was held on April 21 in Ealing, west London, under section 41 of the Terrorism Act, which allows someone to be arrested without a warrant if they are a suspected terrorist, has been released with no further action.
The second suspect, a 37-year-old man who was arrested in Devon on Sunday on suspicion of preparation of terrorist acts, has been bailed until July.
Grainy footage was posted online of the drone being flown in Kensington Park and reportedly crashing into a tree.
Hayi claimed that the drone was carrying hazardous substances, but this later proved to be untrue.
Commander Helen Flanagan, head of Counter Terrorism Policing London, said: “Although these two men have been released from custody, our investigation into this incident continues.
“We appreciate the community remains very concerned about this, and other incidents that have targeted Jewish, Israeli or Iranian sites over recent weeks.
“We have made a total of 26 arrests across our various investigations and we continue to work to identify anyone who may have been involved.”
Of the 26 people arrested, eight have been charged and one convicted.
The two men arrested over the drone incident are the only suspects so far to have been detained under terrorism laws.
