- Syrian opposition says bombs were dropped in Homs province, Hama and Latakia - not ISIL's stronghold, Raqqa.
- Syrian National Coalition says 36 civilians were killed.
- Russia calls rumours targets were not ISIL positions "groundless".
- The US, which leads the coalition fighting ISIL, complained Moscow did not use formal channels to give advance notice of its air strikes to Washington.
Russian Foreign Minister Sergei Lavrov has rejected accusations that Moscow's air strikes in Syria are aimed at targets other than the Islamic State of Iraq and the Levant (ISIL) group and have hit civilians.
"The rumours that the target of these air strikes are not ISIL positions are unfounded," he told journalists after meeting US counterpart John Kerry in New York on Thursday, adding that he has "no data" on civilian casualties.
Saudi Arabia demanded that Russia end its military operations against targets in Syria, a Saudi diplomat said in remarks broadcast by Saudi-owned al-Arabiya television.
Speaking at the United Nations in New York on Wednesday, Abdallah Al-Mouallimi said that the ISIL group was not present in the areas that were attacked by Russian jets.
"The delegation of my country expresses its profound concern regarding the military operations which Russian forces have carried out in Homs and Hama today, places where ISIS (ISIL) forces are not present. These attacks led to a number of innocent victims. We demand it stop immediately and not recur," Mouallimi said.
"As for those countries that have claimed recently to join in the fight against ISIS (ISIL) terrorism, they can't do that at the same time as they support the terrorism of the Syrian regime ... "
US, NATO and the Syrian opposition on Wednesday expressed concern that the Russian bombardments also targeted Western-backed rebels.
President Vladimir Putin called Wednesday's operation a pre-emptive strike against ISIL, and the Russian defence ministry said its warplanes targeted and destroyed eight positions belonging to the group.
US Secretary of State John Kerry said Russia and the US will begin military talks "as soon as possible, perhaps even as soon as tomorrow" to de-escalate the situation, after a meeting with Russian Foreign Minister Sergey Lavrov late on Wednesday in New York.
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The US, which is leading a coalition carrying out air strikes on ISIL in Syria and Iraq, agree with Russia on the need to fight ISIL but not about Syrian President Bashar al-Assad staying in power.
'Doomed to fail'
US Defense Secretary Ash Carter said the Russians appeared to have targeted areas that did not include ISIL fighters.
He said the Russians should not be supporting the Assad government and that their military moves are "doomed to fail".
Lavrov dismissed charges that strikes targeted positions of the Syrian opposition.
Speaking to journalists on the sidelines of the UN General Assembly, he said that the Russian air force was cooperating with the Syrian pro-government military to target "exclusively" ISIL targets, adding that the Russian defence ministry has stated on its website the targets and objectives of its air strikes in Syria.
"Air force jets, equipped with modern technology, carried out strikes on eight targets," the Russian defence ministry said on its website on Wednesday.
"They included weapon and ammunition storages, fuel depos, combat equipment, control points, communication centres and vehicles of ISIL fighters."
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Syrian state news agency SANA reported that Russian jets hit "ISIL dens" around the towns of Talbiseh, Rastan and Salamiyah north of the central city of Homs.
The Syrian opposition National Coalition denounced the Russian air strikes.
"All the targets in today's Russian air raids over northern Homs were civilian," National Coalition president Khaled Khoja wrote on Twitter.
Khoja said 36 civilians had been killed in areas held by neither the Syrian wing of al-Qaeda, the Nusra Front, nor ISIL.
NATO said it was concerned that Russia's air strikes on Syria may not have targeted ISIL positions.
"I'm concerned about the reports saying that the Russian air strikes were not targeted against ISIL," NATO Secretary-General Jens Stoltenberg said during a visit to the United States.
"I'm especially concerned because there has been no real effort by the Russian side to deconflict the Russian air strikes in Syria with the ongoing US-led coalition fighting ISIL," he said.
To "deconflict", in military parlance, is to ensure that, in this case, Russian aircraft do not accidentally clash in any way with Western warplanes.
According to a statement from Assad's office, the Syrian leader had asked Putin for the support.
Source: Al Jazeera and agencies