An Iranian plot to assassinate the American ambassador to South Africa has caused mounting concern after US intelligence reports showed the threat was becoming more specific, US government officials said. Authorities have been aware of the threat against Lana Marks since the spring but in recent weeks intelligence reports have revealed more detailed evidence of the plans to assassinate her, <em>Politico</em> reported, citing two government sources. According to an unnamed official, the Iranian embassy in the South African city of Pretoria is involved in the plot, which is believed to be a retaliation for the assassination of Iranian General Qassem Suleimani in a US drone strike in January. Tensions continued to rise between the two countries following the strike, with the US tightening sanctions on Iran and attempting to extend a UN arms embargo on the country, which is due to expire in October under a 2015 nuclear deal. It’s unclear why the Iranian government would target Ms Marks, a 66-year-old businesswoman who took over the role in October last year. The chief executive and designer of a luxury accessories brand known for producing some of the world’s most expensive handbags, she was nominated for the ambassador's role by President Donald Trump, who she has known for more than two decades. She was also a friend of the late Diana, Princess of Wales. Ms Marks, who has no known links to Iran, has been made aware of the threat against her. It's believed to be one of several attempts being considered by the Iranian government, which operates clandestine networks in South Africa, the officials told <em>Politico</em>. Iran’s history of carrying out overseas assassinations and taking hostages dates back to the 1979 Iranian Revolution, when the current regime seized power. Following the strike at Baghdad Airport, which also killed Iraqi paramilitary chief Abu Mahdi Al Muhandis, President Trump claimed that the Iranian general had been planning attacks against American missions, saying the regime was plotting to blow up US embassies, although this was not proved. The two countries have since stepped up tit-for-tat attacks on military sites inside Iraq. Last month, Gen Kenneth McKenzie, the head of US Central Command, who is also on the Iranian government’s hit list, said he expected a fresh “response” from Tehran to the presence of American troops in Iraq, which is expected to be cut from 5,200 to 3,000 by the end of September as part of Mr Trump’s withdrawal programme.