Iran's chief nuclear negotiator has warned the major Western powers that their policy towards his country's nuclear programme cannot succeed.
Saeed Jalili, speaking in Beijing after talks with Chinese leaders, said the United States and its allies should stop trying to exert pressure on Iran and concentrate instead on diplomatic solutions to the nuclear issue.
"In our talks with China it was agreed that tools such as sanctions have lost their effectiveness," he is quoted by the BBC as saying.
Earlier, US President Barack Obama appealed to his Chinese counterpart, Hu Jintao, for their two countries to work together on the Iranian nuclear issue.
The White House says the two leaders spoke on the telephone for about an hour, with Mr Obama emphasising the importance of Iran living up to its obligations.
There have been signs China may have relaxed its opposition to a new round of United Nations sanctions against Tehran.
The American ambassador to the United Nations, Susan Rice, says China is ready to hold "serious" talks with Western powers on a new UN resolution, the BBC reports.
Ms Rice says senior officials from Britain, the US, France, Russia and Germany reached the agreement with China during a conference call.
China still publicly non-committal
Chinese foreign ministry spokesperson Qin Gang says only that China will continue to push for a peaceful settlement.
China has in the past expressed reluctance to see new sanctions imposed, and as a permanent member of the UN Security Council, along with France, the US, Britain and Russia, it has the power to veto such a move.
Mr Obama has said he hopes to have sanctions in place "within weeks".