Britain has tightened sanctions on five Iranian banks, introducing a presumption that sanctions licence applications involving them will be denied, the UK Office of Financial Sanctions Implementation said in guidance issued on September 23.

The banks are Bank Sepah, Bank Melli, Bank Saderat, Persia International Bank and Bank Tejarat. New licence applications by the banks operating in Britain will be automatically rejected, and an existing general licence will not be renewed, according to Bloomberg, which cited Treasury officials.

The move forms part of the US-led economic pressure campaign aimed at pushing Tehran toward a deal to end the Middle East conflict, Bloomberg reported. It comes as Washington's standoff with Iran continues and traffic through the Strait of Hormuz remains largely blocked.

Iran's central bank governor, Abdolnaser Hemmati, dismissed the move as having no practical effect. He said British banks have had no Iran-related activity for years because of existing sanctions, and that the targeted banks were already unable to operate internationally.

The sanctions tighten as efforts to revive US-Iran talks continue, with Tehran insisting it will not accept what it calls the language of force.