Kemi Badenoch, the leader of the Conservative Party, said she was not against such a move but that “we don’t need to have a ban”.
She said on Monday: “So I’m not against that, but we already have powers within the National Security Act to ban organisations like the IRGC. At the end of the day, they are the army of an enemy country.
“We don’t need to have a ban. There are loads of laws and legislation in place. Let’s use them.”
Reform UK, which leads in the polls, has also backed proscribing the IRGC, with Nigel Farage saying Sir Keir should “stand up to the ayatollah”.
Sir Ed Davey, the leader of the Liberal Democrats, has also urged the Prime Minister to ban the group.
The intelligence and security committee warned last summer that Iran had been behind at least 15 attempts to kill or kidnap people in Britain.
Last May, four Iranian men were arrested on charges of terrorism, while another four were detained over a separate plot to target the Israeli embassy in London.
