Britain's Prime Minister Gordon Brown said on Monday the country will freeze assets of Iran's largest bank in a further move to discourage the country from developing nuclear weapons, after which he also announced additional troops for Afghanistan.

Speaking at a news conference with President George Bush, Brown said Britain will work to persuade Europe to follow in its direction against Iran.

Action will start today in new phase of sanctions on oil and gas. We will take any necessary action so that Iran is aware of the choice it needs to make, Brown said according to AP.

The British leader said that assets of Iran's Bank Melli would be frozen. Last year, the United States accused the bank of providing services to Iran's nuclear and ballistic missile programs.

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 ignore our offers of partnership, we have no choice but to intensify sanctions, said Brown.

President Bush said he wanted to solve the Iranian issue diplomatically but was willing to look at other options.

My first choice is to solve the problem diplomatically but all options are on the table, said Bush. We must prevent the Iranians from having the know-how to create nuclear weapons.

The Iranians must understand that when we come together and speak with one voice, we are serious, he added.

Bush urged Iranian leadership to accept a new package of incentives and said it should accept a Russian proposal to enrich uranium on Iran's behalf.

While referring to the civilian nuclear program, Bush said Iranians say we have a sovereign right to have one, the answer is 'You bet you have a sovereign right, absolutely. But you don't have the trust of those of us who have watched you carefully when it comes to enriching uranium, because you have declared that you want to destroy democracies in the neighborhood.

On Sunday afternoon, Bush arrived in London for a two-day trip to Britain, the last leg of his final tour of Europe before leaving office in January.