By Roland Lloyd Parry
Washington and other powers will turn up the heat on China as they "move away from the engagement track, which has not produced the results that some had hoped for, and move towards the pressure and sanctions track," she said.
"China will be under a lot of pressure to recognise the destabilising impact that a nuclear-armed Iran would have in the Gulf from which they receive a significant percentage of their oil supplies," she added, speaking in Paris.
The United States and its Western allies fear Iran is secretly developing fissile material for nuclear weapons under the cover of its uranium enrichment programme — a charge denied by Tehran.
China, a permanent member of the UN Security Council, has always favoured diplomacy with Iran over sanctions.
Clinton said China was hesitant to jeopardise economic ties with Iran, but urged it to "think about the longer-term implications" for peace in the region.
French President Nicolas Sarkozy told Clinton during a meeting that "the time has come to draw the necessary conclusions from months of vain efforts" to persuade Iran to come clean on its nuclear programme, a French official said.
During a meeting at the Elysee presidential palace on Friday afternoon, the president stressed "the need to move forward at the UN Security Council toward the adoption of a firm resolution on Iran," the official added.
France holds the presidency of the Security Council next month, opening a window of opportunity for it to push through a new fourth round of sanctions against Iran, if China can be brought round.
"We're going to work as hard as we can to get the strongest possible resolution of the Security Council," Clinton told reporters later on Friday, after meeting with France's Foreign Minister Bernard Kouchner.
In London she rallied her European counterparts for sanctions and met with Russian Foreign Minister Sergei Lavrov, who said afterwards that Tehran cannot keep the world waiting forever in the standoff over its nuclear programme.
Arriving in France from London after an international conference on stabilising Afghanistan, Clinton also spoke at a military academy in Paris.
During her address, she urged NATO allies to reach out to Russia for cooperation as part of a broad drive to revitalise European security partnerships.
"We are called to address some of the greatest challenges in human history," such as terrorism and climate change, she said. "To meet them, we are required to modernise and strengthen our (trans-Atlantic) partnership for this new era."
Clinton reiterated the United States' opposition to Russia's call for a new set of security accords for Europe, but said Washington wanted serious cooperation with Russia on missile defence for Europe.
She called for efforts to "revitalise" ties between Russia and NATO to improve cooperation on areas including Afghanistan and anti-missile defence.
"Missile defence will make this continent a safer place. That safety could extend to Russia, if Russia decides to cooperate with us," she added.
"Russia is no longer our adversary but a partner on key global issues."
