Brown, holding his first Downing Street press conference, said he believed sanctions aimed at persuading the Islamic republic to halt uranium enrichment were working. But he also predicted a swift new U.N. Security Council resolution aimed at increasing the pressure on Iran and its hardline president, Mahmoud Ahmadinejad.
Asked about possible military action, he said, "I’m not one who is going forward to say we rule out any particular form of action."
"But I firmly believe that the sanctions we are imposing on Iran are sanctions that are having an effect already," he said. "There will probably be a further resolution in relation to Iran soon, and I believe that is a way forward that is working and will work."
The Security Council already has imposed two sets of sanctions on Iran since December over over its nuclear program. A third resolution is being pushed by the U.S. and its allies who fear Iran is using its civilian nuclear program as a cover to produce atomic weapons.
"Again, I appeal to the Iranian authorities to understand the fears that other countries have about the development of the nuclear weapons program," Brown said.
He said Britain would "take whatever measures are necessary to strengthen the sanctions regime in the future."