Washington has attempted to put more pressure on China over the Iranian nuclear issue by placing sanctions on the country's Bank of Kunlun, with China expressing its strong dissatisfaction and firm opposition to the measures on Wednesday.

The United States is unhappy about China's role in the Iran issue, because they do not think China is putting enough pressure on the country, said Zhang Xiaodong, an expert on Middle East studies with the Chinese Academy of Social Sciences.

"Although the White House didn't say its decision is directed at a third country, the sanction obviously targets China," said Zhang.

The sanction harms the interests of Bank of Kunlun, which belongs to China's largest petrol producer China National Petroleum Corporation, and its main clients include large State-owned enterprises, companies and staff members in the petrol and petrochemical industries, Zhang said.

The US attempted to warn China with its sanction, but it does not want to create direct conflict with China on the Iran issue either, Zhang added.

Shen Peng, a researcher at the Institute of American Studies at the Chinese Academy of Social Sciences, said the US is not happy that Chinese financial firms still have connections with Iran, and want to put more pressure on China.

An editorial published on the Chinese website 21cn.com said the "punishment" serves as a warning to all financial institutions that have business connections with Iran, and the Bank of Kunlun is just a scapegoat.

The White House on Tuesday announced penalties to be imposed on the Bank of Kunlun and an Iraqi bank, blaming them for helping Iran evade international sanctions on its oil exports.

According to the White House, the sanction is not targeted at China, and the US will "expose any financial institution, no matter where they are located, that allows the increasingly desperate Iranian regime to retain access to the international financial system".

A Xinhua News Agency editorial said the sanction does not have a strong legal basis.

"The new measure, purportedly designed to curb Iran's nuclear program, in fact lacks legal grounds ... as sanctions on the Chinese bank and international transactions were made pursuant to the US domestic laws," the editorial stated.

Xinhua said the bilateral economic activities between the Bank of Kunlun and six Iranian banks were conducted in line with a string of UN Security Council resolutions and other international standards.

On Wednesday China hit back at Washington's decision, with Foreign Ministry spokesman Qin Gang releasing a statement saying the sanction seriously violates the international norms and harms China's interests, and China will lodge solemn representation to the US.

China and Iran enjoy normal bilateral relations and have normal, open and apparent business dealings that are not involved with the Iranian nuclear program, and do not violate resolutions of the Security Council or harm the interests of any third party, Qin said.

"China has a consistent and clear position on the issue of non-proliferation, firmly maintains the principals of international non-proliferation system and commits itself with relevant parties including the US to solve the Iranian nuclear issue," the spokesman said.

"But the US ignored China's concerns and repeatedly imposed sanctions on Chinese enterprises and banks — this will yield a negative influence on Sino-US bilateral cooperation," Qin said.

Qin urged the US to correct its erroneous decision, lift the unprovoked sanction against the Bank of Kunlun and stop harming Chinese interests and the Sino-US relations.

"The fourth round of the China-US Strategic and Economic Dialogue held in May yielded positive results and set the tone for expanding strategic cooperation and promoting mutually beneficial relations," Xinhua said in an editorial.

"Washington's sanctions on the Chinese bank would lead to nothing but a hindrance to bilateral cooperation," Xinhua said.

Zhang said China will not give up its interests in Iran, "and is likely to take appropriate countermeasures against the US".

On June 28, US Secretary of State Hillary Clinton announced Washington's last-minute decision to exempt China and Singapore from sanctions over imports of Iranian oil because the two countries had reduced oil purchases from Iran significantly.

With the decision, banks from the two countries can avoid financial sanctions from the US for a renewable period of 180 days. During that time, the two countries can be exempted from sanctions on oil trade transactions with Iran.

According to the US government, Washington will block foreign financial institutions from entering the US financial market, if their governments purchase Iranian crude oil from June 28.

The US is testing China's limit in terms of sanctions on Iran, but the US should know that harming China's core interests is not good for Sino-US ties, said Shen.

Contact the writer at zhouwa@chinadaily.com.cn