The Obama administration is looking to early January as the time to press for a new round of United Nations sanctions against Iran for its continued defiance of demands to explain its nuclear ambitions, US officials said Friday.As US President Barack Obama's year-end deadline looms for Iran to comply with demands to prove its atomic activities are peaceful, the administration is reaching out to European allies, Russia and China to win support for new penalties at the UN Security Council after the council's membership changes January 1, the officials said.Senior US diplomats, including US Secretary of State Hillary Rodham Clinton and her chief deputy James Steinberg, raised the urgency of the matter with European foreign ministers at high-level meetings in Athens, Greece, and Brussels, Belgium, this week ahead of a summit of European leaders.The sanctions package is not yet "coherent," one official said, but may include UN penalties aimed at elements of Iran's Revolutionary Guard Corps, which the United States already has applied, and on Iran's petroleum industry, which the Obama administration is considering.The official said there are still disagreements over how far to push on sanctions, noting that some moves could affect world oil markets. "We are looking to find what everyone can agree will be most effective and have the least impact on the Iranian people," the official said.That official and others spoke on condition of anonymity to describe internal administration thinking on the evolving sanction proposals.The US State Department said Friday the administration was hoping for a strong statement on Iran, including a mention of possible sanctions, from the December 10-11 European Council session in Brussels."There will be a broad discussion on next steps in that meeting," spokesman Ian Kelly told reporters. "The EU is expected to have a written statement on Iran.""Our focus is shifting more toward the pressure track," he said.Senior diplomats moved this week to win backing from Russia and China, which generally are opposed to sanctions and have balked at imposing new penalties.Clinton herself discussed Iran with her Russian counterpart, Sergey Lavrov, on the sidelines of a NATO meeting in Brussels. She is dispatching the third ranking US diplomat, the undersecretary of state for political affairs, William Burns, to Beijing next week.Burns, who represents the United States at meetings of the six-nation group trying to persuade Iran to meet its international obligations, will be in the Chinese capital for talks on Iran and other issues on Tuesday and Wednesday, Kelly said.Burns will try to persuade China to attend another possible meeting of the six-nation group before Christmas to discuss sanctions, the officials said. That meeting could set the stage for a referral of sanctions to the UN Security Council in January. China, though, has so far resisted scheduling it, the officials said.With Iran's continued resistance, its disclosure in September of a secret uranium enrichment plant and its recent threat to build 10 more, US officials believe they can win Russian and Chinese support.An Iranian nuclear official said Friday that Iran will not answer to the UN nuclear watchdog about the plan for new enrichment sites beyond the barest minimum required under the international nonproliferation treaty.The comments by Abolfazl Zohrehvand came days after Iranian President Mahmoud Ahmadinejad said Teheran was considering whether to scale back cooperation with the International Atomic Energy Agency after it approved a resolution censuring Iran because of its nuclear program.