WASHINGTON (AFP) - The United States imposed new sanctions Friday on networks linked to Iran, stepping up pressure over Teheran's controversial nuclear programme.

The Treasury Department said the sanctions target individuals and entities under Iran-related authorities that are involved in Iran's missile and nuclear programmes, efforts to evade international sanctions and support for terrorism.

The White House's National Security Council said that despite the additional measures, the US remained committed to working with its partners in seeking an international deal with Teheran over its controversial pursuit of atomic power.

"Just as we announced these measures and continue to enforce pre-existing sanctions on Iran, the United States remains committed to working with our P5+1 partners toward a long-term, comprehensive solution that provides confidence that Iran's nuclear programme is exclusively peaceful," said Caitlin Hayden, NSC spokeswoman.

The P5+1 group - Britain, China, France, Germany, the United States, plus Russia - last month extended to Nov 24 an interim agreement under which Iran suspended part of its nuclear activities in return for a partial lifting of international sanctions, to allow more time to negotiate a final accord.

Teheran denies that it wants to make nuclear weapons and the sides remain split on how much uranium enrichment Iran should be allowed to carry out.

The Treasury's new sanctions targets include shipping and oil companies, banks and an airline.

"Treasury's action against over 25 entities and individuals - who are involved in expanding Iran's proliferation programme, supporting terrorism in the region, and helping Iran evade US and international sanctions - reflects our continuing determination to take action against anyone, anywhere, who violates our sanctions," said David Cohen, the Treasury's under secretary for terrorism and financial intelligence.