US President Barack Obama has imposed new economic sanctions targeting Iran's oil export sector and a pair of Chinese and Iraqi banks accused of doing business with Tehran.

In a statement released by the White House on Tuesday, Obama said the new measures underlined the United States' determination to force Tehran "to meet its international obligations" in nuclear negotiations.

"This action is designed to deter Iran from establishing payment mechanisms for the purchase of Iranian oil to circumvent existing sanctions," Obama said, warning that US sanctions will be apply to any entity buying Iranian oil.

He said measures would be taken against firms that have dealings with the National Iranian Oil Company, the Naftiran Intertrade Company or the Central Bank of Iran or that help Iran buy US dollars or precious metals.

And he accused the Bank of Kunlun in China and the Elaf Islamic Bank in Iraq of arranging transactions worth millions of dollars with Iranian banks already under sanctions because of alleged links to Tehran's weapons program.

Obama said these two institutions would henceforth be denied access to the US financial system.

"The United States remains committed to a diplomatic solution, but the onus is on Iran to abide by its international obligations," he said.

"If the Iranian government continues its defiance, there should be no doubt that the United States and our partners will continue to impose increasing consequences," he warned.

AF

Originally published as US sets new sanctions on Iran oil sector