Beijing  - China wants a diplomatic solution to Iran's building of a previously undeclared uranium-enrichment facility and opposes any tough international sanctions that would stop Iran from exporting oil, experts and state media said on Wednesday.

China will oppose new sanctions if the United States proposes a ban on Iran exporting oil, the Global Times quoted Yin Gang, an expert on Middle East affairs at the Chinese Academy of Social Sciences, as saying.

Yin said the possibility of a proposed ban on oil exports was low, but said China needed to balance its warming political ties with the United States and its economic links with Iran.

"China has voted for the three UN Security Council resolutions on Iran despite the fact that China regards Iran as a friend, and has called for peaceful dialogue to address the issue," he said.

China's agreement to a fourth resolution to impose new sanctions on Iran would depend upon whether the United States "insists on tough action" and whether Iran "remains defiant," Yin said.

"Iran is an important economic and trade partner of China," Tian Wenlin of the China Institute of Contemporary International Relations told the German Press Agency dpa.

"All cooperation between the two countries abides by international laws and regulations, which should not be criticized by any third party," Tian said.

Yin was quoted as saying that China might be unhappy with other proposed sanctions such as a ban on exporting petrol and diesel to Iran, which "may hurt China's economic interests."

Foreign Ministry spokeswoman Jiang Yu on Tuesday said China hoped for "positive gains" from Thursday's talks in Geneva between Iran and the five permanent UN Security Council members plus Germany.

"We hope the parties will increase diplomatic efforts and push the talks toward positive gains," Jiang told reporters, adding that a proper solution to the Iranian nuclear issue would "serve the interests of all parties."

Cheng Jingye, head of the Foreign Ministry's Department of Arms Control, was scheduled to represent China at the talks, she said.

Tian warned that Iran's continuation of its nuclear programme suggested that it would not compromise and that US President Barack Obama's was "softer than his predecessor."

"So for Iran, they know it is a good time to bargain now," Tian said. (dpa)