The United States has announced fresh sanctions against Iran's energy sector and warned firms against dealing with Iran's financial sector.
US Secretary of State Hillary Clinton, unveiling what she called a "significant ratcheting up of pressure on Iran," said the US was targeting Iran's energy sector directly for the first time.
"Recent days have brought new evidence that Iran's leaders have continued to defy their international obligations," said Mrs Clinton.
Detailing sanctions against goods, services and technologies for the vital petrochemical sector, Mrs Clinton said "there have to be consequences of such behaviour".
Iran's energy sales are thought to account for around 70% of the government's budget and are crucial to the Iranian economy.
US Treasury Secretary Timothy Geithner also issued a warning that any firms doing business with Iran's banking sector could run the risk of funding illicit activities.
The US government named Iran as "a primary money laundering concern," but stopped short of adopting fully blown sanctions against Iran's central bank.
"Financial institutions around the world should think hard about the risks of doing business with Iran," said Mr Geithner.
