London  - British companies have been banned from doing business with two Iranian firms linked to Tehran's nuclear programme, Exchequer Secretary Sarah McCarthy-Fry announced late Monday.

The two Iranian firms being targeted are Bank Mellat and the Islamic Republic of Iran Shipping Lines. Both allegedly have supported the Iranian government's nuclear and ballistic missile programmes.

McCarthy-Fry accused the shipping line of using its vessels to carry goods for Iran's ballistic missile and nuclear programmes, and the bank of providing financial services.

British companies are prohibited from entering into new ventures with the two firms, and existing business relationships must be severed unless specially authorized by the British Treasury.

"We cannot and will not ignore specific activities by Iranian companies, which we know to be facilitating activity identified by the UN as being of concern, particularly where such activities have the potential to affect the UK's interests," McCarthy-Fry said. (dpa)