Russian Foreign Minister Sergei Lavrov says the UN decision to withdraw an invitation to Iran to attend peace talks on Syria was a "mistake" but not a "catastrophe."
Speaking at a press conference in Moscow on January 21, Lavrov said Ban's reversal "did not boost the authority" of the United Nations.
He also said the decision would deepen divisions in the Muslim world and would not held the fight against terrorism.
"This is, of course, a mistake," Lavrov, whose country has generally stood with Iran alongside embattled Syrian President Bashar al-Assad in the face of international criticism, said. "I have talked about this earlier. But it is not a catastrophe."
Ban's offer of an invitation to Iran had cast doubt over the talks due to begin on January 22 in Switzerland.
It angered the United States, while the Western-backed Syrian opposition threatened to boycott the conference.
Ban said he had invited Iran after receiving assurances that Tehran had accepted the goal of establishing a transitional government that does not include President Assad. He revoked the invidation late on January 20 after Iran said it would not accept preconditions to the talks.
Lavrov said recalling the offer looked "unseemly." He reiterated Russia's position that the participation of Iran was essential for the success of the talks.
Iranian Foreign Minister Mohammad Javad Zarif said Ban had withdrawn the invitation to Iran "under pressure." He said it was "regretful" the UN chief "does not have the courage to provide the real reasons for the withdrawal."
A deputy Iranian foreign minister, Abbas Araqchi, predicted on January 21 that the chances of peace talks succeeding without Iran were "not that great."
Iran is Assad's main regional ally. Russia is also a key ally and has continued to supply Damascus with weapons throughout the conflict, which is estimated to have killed more than 130,000 people.
The talks in Switzerland would put the Syrian government and the opposition at the same table for the first time since the start of the uprising against Assad's regime three years ago.
Meanwhile, a report by three former international war crimes prosecutors says evidence smuggled out of Syria shows that about 11,000 detainees have been executed there since the beginning of the that country's uprising three years ago. The report is based on thousands of Syrian government photographs and files recording deaths in custody.
One of the authors of the report, Desmond de Silva, a former chief prosecutor of the special war crimes tribunal for Sierra Leone, told Britain's "The Guardian" daily that the evidence "documented industrial-scale killing."
The evidence was smuggled out of Syria by a former police photographer who fled the country.
Based on reporting by ITAR-TASS, Interfax, Reuters, AFP, and AP