* Russia says Iran, 6 powers advanced in technical talks
* Warns of danger of backsliding despite upbeat mood
* Says "plenty of homework" before April talks
* Iran seems cool to offer of limited sanctions relief
By Steve Gutterman
MOSCOW, March 21 (Reuters) - Russia said on Thursday that
Iran and six global powers made progress in expert-level talks
this week on the standoff over Tehran's nuclear programme but
there was no breakthrough and that backsliding remained a
"This progress is real but it is not sufficient to speak of
a definitive shift," Deputy Foreign Minister Sergei Ryabkov,
Russia's chief negotiator on the issue, said of the talks in
Istanbul on Monday.
"We cannot say this progress is irreversible. This alarms us
a little, but from round to round, we have a more and more
businesslike discussion of all the issues," he told reporters.
Russia, the United States, Britain, France, Germany and
China are spearheading diplomacy meant to ensure that Iran,
which says its nuclear programme has purely peaceful ends,
neither seeks nor achieves nuclear weapons capability.
In Istanbul, the six powers gave Iran more details of
proposals made at political-level talks in late February in the
Kazakh city of Almaty, where they offered Tehran modest
sanctions relief if it curbs its most sensitive nuclear work.
Ryabkov said the sides had "plenty of homework to do" before
the next meeting at a political level, in Almaty on April 5-6,
but suggested the technical talks had laid some good groundwork.
"When there is movement in talks, you do your homework in a
good mood, and not like a failing student who is about to get
kicked out of the classroom anyway," he said.
"It was a very useful event, ending on a positive note,"
said Ryabkov, who welcomed what he called "Iran's display of
readiness to conduct concrete dialogue."
Russia, which built Iran's first nuclear power plant and has
better relations with Tehran than do Western powers, has tended
to be more upbeat than Western leaders about Iran's attitude
toward the negotiations.
Western officials have said the offer presented by the six
powers in Kazakhstan included an easing of a ban on trade in
gold and other precious metals, and a relaxation of an import
embargo on Iranian petrochemical products.
In exchange, a senior U.S official said, Iran would among
other things have to suspend uranium enrichment to a fissile
concentration of 20 percent at its Fordow underground facility
and "constrain the ability to quickly resume operations there".
Iran has hinted it is not satisfied with the powers' offer,
although chief negotiator Saeed Jalili said after last month's
Almaty talks that the six had tried to "get closer to our
viewpoint" and that, he added, was positive in itself.
Western diplomatic sources said experts had engaged in
detailed technical talks about the powers' proposal in the
Istanbul meeting, but it was unclear whether this would lead to
substantive results at the political talks in early April.
The European Union, whose foreign policy chief Catherine
Ashton oversees contacts with Iran for the six powers, has given
no public indication of whether there was progress in Istanbul.
Russia went along with four rounds of U.N. Security Council
sanctions against Iran over its nuclear programme but opposes
further sanctions and has sharply criticised separate Western
sanctions, saying they are counterproductive.
(Additional reporting by Fredrik Dahl in Vienna; Editing by