Iranian Oil Minister Massoud Mir-Kazemi met Chinese Vice Premier Li Keqiang and other officials on Friday, with both sides pledging to expand cooperation, dpa reported
Iran was an "important energy supplier" and "one of the most important trade partners of China in western Asia," state broadcaster China Central Television quoted Li as telling Mir-Kazemi.
"In recent years, trade cooperation was very fruitful," Li said.
China wanted to expand cooperation, "enhance political trust (and) maintain negotiations and contacts on major issues" with Iran, he said.
The report gave no details of any bilateral agreements signed between the two sides.
The China Daily newspaper quoted Yin Gang of the Chinese Academy of Social Sciences as saying the visit was mainly aimed at attracting more Chinese investment for oil refineries in Iran.
Medhi Safari, Iran's ambassador to China, told the newspaper earlier this week that Iran "welcomes foreign investment in different areas, such as telecommunications, transportation and energy" from China and other nations.
China has opposed the additional unilateral sanctions announced by the United States and the European Union over Iran's nuclear programme.
On Wednesday, China's Foreign Ministry said the country would continue "normal" trade with Iran but abide by sanctions imposed by the United Nations Security Council.
"China's trade with Iran is normal business exchange, which will not harm the interests of other countries and the international community," ministry spokeswoman Jiang Yu said in a statement.
"As a permanent member of the UN Security Council, China has always observed the council's resolutions," Jiang said.
"The US and the EU have no right to urge China to observe the resolutions they unilaterally made, which went beyond the UN sanctions," Zhang Xiaodong, deputy chief of the Chinese Association for Middle East Studies, told China Daily.
"China aims to prompt the Iranian government to drop its nuclear ambitions without affecting Sino-Iranian trade and the daily lives of the Iranian people," Fu Mengzi, a US specialist at the China Institute of Contemporary International Relations, told the newspaper.
Mir-Kazemi arrived in Beijing on Thursday accompanied by the head of the National Iranian Oil Company, reports said.
Iran's deputy oil minister said last week that oil exports to China shrank by about 30 per cent year-on-year to 9 million tons in the first half of this year.
Yin said shrinking oil output was the main reason behind China's reduced oil imports from Iran, rather than changes in China's oil importing strategy