The defence ministry did not make any mention of the possible death of Islamic State chief Abu Bakr al-Baghdadi, after saying on Friday that it was seeking to verify whether he had been killed in a night raid in Syria in May.
Asked about that claim at a Moscow news conference, Russian Foreign Minister Sergey Lavrov said: "I don't have a 100 percent confirmation of the information".
Reuters reported that the drones were used on May 28 to confirm the intelligence report on the venue and the time of the meeting with the Islamic State leaders.
There have been previous reports of al-Baghdadi's death, which turned out to be untrue.
The statement came a day after Russian Federation said it may have killed ISIS leader Abu Bakr al-Baghdadi in an air strike last month.
"The Russians are trying to improve their record fighting Daesh as it was the Americans who have killed the top commanders of the group so far, like Abu Omar al-Shishani, Abu Muslim al-Turkmani, Abu Mohammed al-Adnani and Abu Ali al-Anbari", he said, using an Arabic acronym of ISIS.
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The group's current No. 2 is believed to be Ayad Abdul-Rahman al-Obeidi, also known as Abu Saleh Haifa, a former Iraqi army officer under Saddam Hussein.
Both are under attack by various groups who are fighting under the cover of airstrikes by the US -led coalition. There has been no official comment from Syria's government, the BBC reported.
"Lately, Baghdadi has only been ISIS' image, while the actual leadership of the organization in Syria and Iraq is in the hands of a 12-member council that plans and orders everything related to the group", the founder of the Euphrates Post, Ahmad al-Ramadan, told Asharq Al-Awsat.
"According to information which is being checked through various channels, the leader of ISIL (IS) Ibrahim Abu Bakr al-Baghdadi was also present at the meeting and was eliminated by the strike". Reports suggest he was radicalised during the four years he was held at Camp Bucca, a USA prison in southern Iraq where many al-Qaeda commanders were detained.
In October 2011, the USA officially designated Baghdadi as a terrorist.
However, in the case of IS spokesman Abu-Muhammad al-Adnani, the group rushed to announce his death on 30 August 2016, the same day he was targeted in a United States air strike in Syria, pre-empting any reports by the military or media. It has offered a reward of up to $25m (£19.6m) for information leading to his capture or death.
Western sources said they could not corroborate the death while Iraqi officials said they were sceptical about reports about the secretive leader.