China has urged Iran to co-operate with the UN's nuclear agency to settle a standoff over its nuclear programme, reports BBC.
Chinese Foreign Minister Li Zhaoxing said there was still room to negotiate.
The International Atomic Energy Agency (IAEA) is meeting in Vienna for talks that could pave the way to UN Security Council action against Iran.
The issue is expected to dominate talks between Russia's foreign minister, US Secretary of State Condoleezza Rice and President George Bush in Washington. China has appealed for all sides in the dispute to remain calm.
There is still time for a settlement of the issue within the framework of the IAEA
Speaking at a press conference in Beijing, Li said: "We hope Iran will cooperate closely with the IAEA and adopt more measures that are helpful to building confidence.''
"There is still time for a settlement of the issue within the framework of the IAEA."
Russia and China - permanent members of the Security Council with the power of veto - have so far opposed imposing sanctions on Iran.
Following talks in Vienna Monday, the head of the IAEA, Mohamed ElBaradei, said he was hopeful a deal was still feasible.
The BBC's Bethany Bell says some diplomats at the IAEA, including Mr ElBaradei, appear cautiously optimistic that an agreement on Iran's sensitive uranium enrichment work could still be within reach.
Western powers believe Iran wants to develop nuclear arms, a claim it denies.
Tehran insists it has the right to develop its nuclear sector to produce energy for civilian purposes.
In Washington, the nuclear standoff with Iran is likely to be high on the agenda for talks with Russia's Foreign Minister Sergei Lavrov.
Under a new Russian proposal, Iran would be permitted to undertake small-scale uranium enrichment without obtaining the technology to build nuclear weapons.
The US has said that only a complete suspension of Iran's nuclear activities would be acceptable in order to avoid UN Security Council action.