"Our general impression is that there is a very good chance that must not be missed," the Interfax news agency reported Lavrov as saying.
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"Now there are no fundamental disagreements on the practical questions that need to be resolved," he said.
All that is necessary now is to "correctly draw up the agreement we have reached in diplomatic language," he said.
Yet he warned against adding further conditions for Iran to comply with when talks on curbing its nuclear program resume in Geneva on Wednesday.
Lavrov said the talks should not focus on "submitting some artificial additions that do not help solve the main task and don't essentially change anything."
Some reports said that the talks ended in deadlock because of reservations expressed by France which were subsequently adopted by other powers.
A Russian foreign ministry source said Tuesday that the failure to agree a historic deal at the talks in Geneva that ended on Sunday was "not the fault of the Iranians."
The so-called P5+1 group negotiating with Tehran is made up of the five permanent members of the UN Security Council - Britain, China, France, Russia and the United States -- plus Germany.
This year's election of new Iranian President Hassan Rohani, seen as a moderate, has given fresh impetus to the negotiations which had faltered in recent years.
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