“Today we are announcing sanctions against corrupt Iranian banker and businessman, Aliakbar Ansari, for his role in financially supporting the activities of the IRGC," minister of state for the Middle East in the UK foreign office Hamish Falconer said in a statement.
"The IRGC is one of the most powerful military organizations in Iran, reporting directly to the Supreme Leader. Its use of repression and targeted threats to carry out hostile acts, including here in the UK, is completely unacceptable," he added.
Ansari, 63, will now be subject to an asset freeze, disqualification from any UK company ownership and a travel ban. He holds multiple passports, including from Iran, St Kitts and Nevis, and Cyprus the foreign office added.
The British government said last month it was determined to frustrate what it called escalating Iranian threats to people on UK soil, citing cyberattacks and the use of criminal proxies to carry out attacks.
The government in March designated the Iranian state in its entirety on the enhanced tier of its new Foreign Influence Registration Scheme (FIRS). 
The move means anyone working for or directed by the Iranian state to conduct activities in the UK must declare those activities or face up to five years in prison.