* Lavrov says six powers, Iran close to preliminary deal
* Indicates agreement would set guidelines for resolution
* After years of talks, U.S. also says a deal possible
Global powers and Iran are close to a preliminary deal to rein in Tehran's nuclear programme and should not pass up a "very good chance" to clinch it, Russian Foreign Minister Sergei Lavrov said in remarks broadcast on Saturday.
His upbeat comments in a television interview came a day after a senior U.S. official said it was possible a deal could be reached when negotiators meet in Geneva from Nov. 20.
Six nations negotiating with Iran hope the talks can produce an agreement that would be the first step towards a comprehensive deal to end a decade-long standoff with Tehran and provide assurances it will not build nuclear weapons.
"Our common impression is that there is a very good chance that must not be passed up," Lavrov said of a recent discussion with European Union foreign policy chief Catherine Ashton, when asked whether the Geneva talks could be successful.
"The steps that must be taken to defuse the situation and create conditions for a final resolution of the Iranian nuclear problem are clear to both the six nations and Iran," he said in the interview with Moscow-based TV Tsentr.
"It is a matter of putting this on paper correctly, accurately and in a mutually respectful way."
Ashton represents the six global powers seeking to curb Iran's nuclear programme - the United States, Russia, China, Britain, France and Germany - in negotiations with Tehran.
Talks on Nov. 7-9 produced no deal but "confirmed that for the first time in many years both the six nations and Tehran are ready not just to present positions that in most cases do not intersect, but to find points of intersection," Lavrov said.
"These points have been determined, and now there are no fundamental disagreements on which issues need to be resolved in practice," he said, according to a Foreign Ministry transcript of the interview.
He gave no details. Iran wants relief from U.S., EU and U.N. sanctions imposed for violating U.N. resolutions demanding it halt uranium enrichment and other sensitive nuclear activities that could be used to make weapons.
Iran denies it wants to develop atomic weapons capability and insists its nuclear programme is dedicated exclusively to the peaceful generation of electricity and other civilian uses.
Russia, which built Iran's first nuclear power plant and has much warmer ties with Tehran than the United States does, backs Iran's desire for recognition of its right to enrich uranium and opposes any additional sanctions.
Iran has stopped expanding its uranium enrichment capacity under President Hassan Rouhani, who replaced hardliner Mahmoud Ahmadinejad in August, an International Atomic Energy Agency report showed on Thursday.