Declaring that Iran "couldn't care less" about UN sanction threats, President Mahmoud Ahmadinejad said on Wednesday Iran had 3,000 centrifuges up and running for uranium enrichment.

The number is a milestone because scientists say that in ideal conditions it is sufficient to produce enough enriched uranium in one year to make a single nuclear bomb.

"We have taken note of the developments and we request Iran to positively respond and attach importance to the concerns of the international community," Chinese foreign ministry spokesman Liu Jianchao told a regular press briefing.

Ahmadinejad has made the centrifuge claim previously, but his latest statement has been seen by some parties, particularly the United States, as especially provocative as tensions have spiked recently over the issue.

The United States is pressing for tough new UN sanctions and has not ruled out a military strike on Iran, while Ahmadinejad recently said any such strike would face a strong response and threatened Iran could cut off Persian Gulf oil shipments.

Asked whether China might be any closer to abandoning its outright opposition to sanctions, Liu reiterated Beijing's preference for negotiations.

"We also hope the relevant parties, through peaceful means including dialogue and consultation, can peacefully settle this issue," he said.

Iran has so far defied international calls to suspend uranium enrichment, saying its programme is solely for civilian energy purposes.

Although it opposes a nuclear-armed Iran, energy-hungry China has consistently opposed tough action against the Mideast state, a potential major supplier of oil and gas.