U.S. President George W. Bush won Europe's backing on Monday for tighter sanctions on Iran over its nuclear programme and secured a British pledge to send more troops to Afghanistan.
After talks with Bush on the last day of the president's farewell tour through Europe, Prime Minister Gordon Brown said European states would agree to impose financial sanctions on Tehran.
"So today, Britain will urge Europe and Europe will agree to take further sanctions against Iran," he told a news conference. "First of all we will take action today that will freeze the overseas assets of the biggest bank in Iran, the bank Melli."
Iran has ignored calls to stop enriching uranium, a process that can be used to make nuclear weapons, and says its nuclear programme is intended only for civilian purposes.
Tehran again ruled out suspending enrichment on Saturday, ignoring political and economic incentives put forward by six world powers including the United States and Britain.
"We will do everything possible to maintain the dialogue, but we are also clear that if Iran continues to ignore united resolutions and continues to ignores our offers of partnership, we have no choice but to intensify sanctions," Brown said.
European foreign ministers were due to discuss Iran at a meeting in Luxembourg. A Foreign Office spokesman said London, its EU partners and Washington were discussing a range of additional sanctions, including in the oil and gas sector.
European Union foreign policy chief Javier Solana was due to brief the ministers after visiting Iran at the weekend, when he said he expected a formal reply soon on the incentives package,
A senior member of Iran's parliament, Alaeddin Boroujerdi, has said Tehran is in no hurry.
Italian Prime Minister Silvio Berlusconi, French President Nicolas Sarkozy and German Chancellor Angela Merkel have all offered Bush support for efforts to prevent Iran, the world's fourth-largest oil producer, obtaining nuclear weapons.
