A third person has been arrested in connection with an attempted arson attack at Finchley Reform Synagogue in north London last month, the Metropolitan Police said.
A 19-year-old man was arrested in Portsmouth this morning on suspicion of attempted arson and is in custody.
No damage was caused to the building and no injuries were reported after the incident on April 15.
A man, 46, and a woman, 38, were arrested at an address in Watford on the same day on suspicion of arson endangering life. They are on bail to a date in July.
The investigation is being led by counter-terror police.
Commander Helen Flanagan, head of Counter Terror Policing London, said: "We are continuing to make progress in all our ongoing investigations linked to various recent arson attacks across London.
“Counter-terrorism officers continue to work closely with our colleagues in the Metropolitan Police in response to the incidents. We’re providing protective security advice and support to various organisations, community venues and businesses.
“With the threat level now raised to severe, everyone can play their part to keep themselves and their communities safe. If you have concerns about someone behaving suspiciously, please report it to us. Your information could help us save lives.”
