Beijing reacted furiously Wednesday to new US sanctions imposed on a Chinese bank over transactions with Iran, urging Washington to revoke them and saying it would lodge an official protest.
China's foreign ministry urged the United States to lift the sanctions on the Bank of Kunlun, which it said violated the "norms of international relations" and damaged relations between Beijing and Washington.
US President Barack Obama on Tuesday imposed new economic sanctions on Iran's oil export sector and on a pair of Chinese and Iraqi banks accused of doing business with Tehran.
Obama said the new measures underlined the United States' determination to force Tehran "to meet its international obligations" in nuclear negotiations, according to a statement released by the White House.
The US president accused the Bank of Kunlun 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.
In a brief statement, China's foreign ministry expressed "strong dissatisfaction and firm opposition" to the US move and said it would officially protest the decision.
"Citing its domestic law, the US imposed sanctions on a Chinese financial institution, which seriously violates the norms of international relations and damages China's interests," the ministry said.
"China has regular relations with Iran in the energy and trade fields, which have no connection with Iran's nuclear plans," it added.
The banking dispute comes after Washington and Beijing clashed last month over proposed United Nations' sanctions against Syria, which were vetoed by China and Russia, provoking criticism by the Obama administration.
The US has steadily worked to punish Iran over its nuclear development, which it has describes as a key global security threat.
Iran says it has a right to enrich uranium for civilian nuclear energy and research. Western powers, however, fear it is attempting to stockpile enough highly-enriched fuel to have a "break-out capability" to build a bomb.
The latest sanctions came on the same day the US State Department branded Iran "an active state sponsor of terrorism" in its 2011 annual terrorism report.
Separately, the US Treasury Department said that Bank of Kunlun provided services to at least six Iranian banks that have been placed under US sanctions because of their alleged roles in Iran's weapons of mass destruction programs.
Bank of Kunlun declined to comment on the announcement to impose sanctions.