The UK Government has imposed fresh sanctions (on top of the existing EU sanctions against Iran) which effectively lead to a severance of all financial ties between UK financial institutions and Iranian banks. On the basis of a recently released report on Iran by the International Atomic Energy Agency and well publicised concerns about the country's nuclear programme, the UK Treasury has concluded that financial activities which facilitate the development or production of nuclear weapons pose a significant risk to the national interests of the United Kingdom, noting there is strong evidence that Iran's banking sector is actively supporting the country's nuclear weapons programme.

As a result, as of 3.00 p.m. on 21 November 2011, every UK credit and financial institution will be required to cease all transactions with banks incorporated in Iran as well as their branches and subsidiaries. The gravity of the sanctions is evidenced by the fact that this is the first occasion when the UK uses powers created under the 2008 Counter Terrorism Act to isolate an entire country's banking sector in such a manner.