These attempts have escalated dramatically since 2022, with even US President Donald Trump among the alleged targets. In the UK, police are questioning a number of Iranians arrested earlier this month on suspicion of planning a terrorist attack. The BBC understands the alleged target was the Israeli embassy in London.

And court documents from Turkey and the US - seen by BBC Eye Investigations and BBC Persian - contain evidence that Iran has been hiring criminal gangs to carry out killings on foreign soil, allegations the Iranian regime has previously denied. Iranian officials did not respond to a fresh request for a comment. One name repeatedly surfaced in these documents: Naji Sharifi Zindashti, an Iranian criminal boss, known for international drug smuggling.

His name appeared in a Turkish indictment in connection with the 2017 killing in Istanbul of Saeed Karimian, the head of a Persian TV network that broadcast Western films and programmes to Iran. Iranian authorities considered Karimian a threat to Islamic values, and three months before his assassination an Islamic Revolutionary Court in Tehran sentenced him in absentia to six years in prison. US and Turkish officials believed his death was related to a mafia feud. (BBC)