The United States, Britain and Canada announced new measures against Iran's energy and financial sectors Monday and France proposed "unprecedented" new sanctions, including freezing the assets of its central bank and suspending purchases of its oil.

The news pushed benchmark Brent crude above $107, reflecting concerns about escalating tensions with the world's fifth biggest exporter.

Critics of the sanctions said they would fail to stop Iran's nuclear work and would play into the hands of a government that wears its hostility to Washington as a badge of pride.

"Such measures are condemned by our people and will have no impact and be in vain," Foreign Ministy spokesman Ramin Mehmanparast told a news conference. "They will have no impact on Iran's trade and economic ties with other countries."

The latest sanctions were prompted by a U.N. nuclear agency report that suggested Iran had worked on an atomic bomb design. Tehran maintains its work is entirely peaceful and said the report was based on false Western intelligence.

"If our people feel that enemies want to deprive them of their rights by threatening, bullying and adopting illegal and irrational methods, they will pursue the path that they have taken, more united and more determined than ever," Mehmanparast said.