BEIJING China denounced the United States on Tuesday for imposing its own sanctions on Iran, saying Washington should not unilaterally take such steps outside of U.N. resolutions.
Last week, President Barack Obama signed into law far-reaching new sanctions on Iran that aim to squeeze the Islamic Republic's fuel imports and deepen its international isolation.
"China has already noted that the United States and other parties have unilaterally put in place further sanctions against Iran," Chinese Foreign Ministry spokesman Qin Gang told a news briefing in Beijing.
"Not long ago, the U.N. Security Council approved resolution 1929," Qin said, referring to sanctions placed on Iran last month. "China believes that the Security Council resolution should fully, seriously and correctly be enforced and cannot be wilfully elaborated on to expand Security Council sanctions measures."
The U.S. House of Representatives and the Senate approved the new sanctions bill that penalizes companies supplying Iran with gasoline as well as international banks involved with Iran's Islamic Revolutionary Guard Corps.
It came after the U.N. Security Council passed a resolution toughening sanctions on Iran over its refusal to stop enriching uranium.
Iran insists its nuclear programme is for the peaceful generation of electricity but the United States and other powers suspect it is a cover to build an atomic bomb.
Qin repeated that China believed talks were the best way to resolve the dispute over Iran's nuclear activities.
Iran is a major supplier of crude to China, the world's second-biggest consumer of oil after the United States, providing over 10 percent of imports last year.
Dominated by energy shipments, bilateral trade has grown from around $10 billion in 2005 to more than $20 billion last year.
(Reporting by Ben Blanchard and Huang Yan; Editing by Nick Macfie)