Iranian President Mahmoud Ahmadinejad announced on Thursday that Iran was capable of enriching uranium to more than 80 percent purity, coming close to levels experts say would be needed for a nuclear bomb, although he said that was not the country's intention.
"I believe the mood around the world is now increasingly one where, patience not being inexhaustible, people are turning to look at the specific sanctions we can plan on Iran," Brown told BBC TV.
""This is a critical time for Iran's relationship with the rest of the world."
Brown said the international community did not want to impose sanctions but would do so if Iran did not cooperate more fully over its nuclear plans.
(Reporting by Matt Falloon; editing by Keith Weir)
