Sir Keir Starmer has told of his growing “concerns” that countries are using proxies to target the UK as he visited a London synagogue hit by an arson attack.
The Prime Minister condemned “malign state actors” as he met people at Kenton United Synagogue in Harrow, north-west London, which was attacked on Saturday.
It was the latest in a series of recent arsons at Jewish sites in the capital.
The security services and counter-terrorism police are investigating whether a shadowy group called Harakat Ashab al-Yamin al-Islamia, the Islamic Movement of the Companions of the Right, is behind the attacks.
It is suspected of acting as a proxy for Iran’s hardline military force, the Islamic Revolutionary Guard Corps, and of recruiting people in the UK to carry out attacks.
The UK’s anti-terror laws chief Jonathan Hall has firmly pointed the finger at Tehran for being behind the attacks.
“It looks as if this is a highly coordinated set of measures that have been taken by Iran against countries that they would see as their adversaries,” he said.
Since late March, there have been arson attacks on Jewish community ambulances in Golders Green, north-west London, a synagogue and a former Jewish charity, as well as an incident where a drone was flown near the Israeli embassy.
Speaking at the Kenton United Synagogue on Thursday afternoon, Sir Keir said: “We have to deal with malign state actors, that will require legislation.
“We’re going to bring that legislation forward. It’s really important we do that. It’s very important this particular context because I’m increasingly concerned that a number of countries are using proxies for attacks in this country.”

Mr Hall has been urging the Government to proscribe the Islamic Revolutionary Guard Corps under new legislation which could also be used against the Islamic Movement of the Companions of the Right.
Sir Keir said counter-terrorism police and the Jewish charity the Community Security Trust are working together after the series of attacks.
He said the Government will bring forward the legislation on the use of proxies “as quickly as possible” as well as taking steps to tackle antisemitism and change the law on protests.
He said: “I want this country to be a place where everybody feels safe and secure.
“This is not just a battle for the Jewish community. It is our battle.

“The Britain that I want is a Britain where people can practice their religion, their faith, in safety and security, and we must stand with and alongside our Jewish community here, and that’s amongst the reasons I wanted to come here personally myself this afternoon to hear first hand from the people affected by the attack this weekend.”
Premises linked to people opposing the Iranian regime have also been targeted, the Metropolitan Police said earlier this week.
An attempted arson attack was also carried out on April 15 at Finchley Reform Synagogue, and at about 8.30pm outside the offices of a Persian media company, both in north-west London.
On Tuesday, a 17-year-old boy pleaded guilty at Westminster Magistrates’ Court to arson not endangering life following the attack on Kenton United Synagogue.
The Jewish community in London has prepared for a chemical weapons attack amid the the sharp rise in incidents of anti-semitism and terror threats.
Britain’s security services have already disrupted more than 20 Iranian state-backed terror plots in a year, including alleged assassination attempts targeting individuals in London.