Brown in Iran sanctions warning

The premier made clear the UK would also urge both the EU and the United Nations to impose tougher sanctions on financial sector dealings with the country.

"Iran should be in no doubt about the seriousness of our purpose," he told the Lord Mayor's banquet in the City of London.

Mr Brown said the moves should follow unless there were "positive outcomes" from both an EU and an International Atomic Energy Authority report into Iran's nuclear programme, due to be published shortly. "We will lead in seeking tougher sanctions both at the UN and in the European Union, including on oil and gas investment and the financial sector," he said.

The Prime Minister, in his most wide-ranging foreign affairs speech since taking office, summed up his approach as "hard-headed internationalism".

On Pakistan, Mr Brown urged President Pervez Musharraf to step down as head of the army, restore the constitution, free political prisoners and hold "free and fair elections" in January.

The premier repeated long-standing British calls for reform of international institutions - such as expanding the UN Security Council to include African countries and major economies such as Japan and Germany.

Mr Brown also said the G8 group of leading industrialised democracies had to continue to broaden its horizons. And he called for greater emphasis on reconstruction teams and moves to "prevent breakdowns of states and societies".

The Prime Minister said: "My approach is hard-headed internationalism - internationalist because global challenges need global solutions and nations must cooperate across borders - often with hard-headed intervention - to give expression to our shared interests and shared values. And hard-headed because we will not shirk from the difficult long term decisions and because only through reform of our international rules and institutions will we achieve concrete, on-the-ground results."

Stressing the importance of the UK's relationship with the United States, Mr Brown made clear: "It is no secret that I am a lifelong admirer of America. I have no truck with anti-Americanism in Britain or elsewhere in Europe and I believe that our ties with America - founded on values we share - constitute our most important bilateral relationship. And it is good for Britain, for Europe and for the wider world that ... France and Germany and the European Union are building stronger relationships with America."