De Mistura, the UN's envoy to Syria, said on Wednesday that a ceasefire brokered by the US and Russia needs to be "revitalized" before peace talks resume next month.

His comments came after a briefing with the UN Security Council about the status of the third-round talks, which he insisted have made progress despite recent hurdles.

The peace talks kicked off again two weeks ago, the same day the regime of Syrian President Bashar al Assad held much-criticized parliamentary elections. At the time, de Mistura said he hoped the talks would allow oppsosition leaders and representatives of Assad's regime to chart a political transition in the country.

Little progress?

However, renewed violence has stalled negotiations, as opposition leaders accuse the Assad government of targeting civilians even as its representatives in Geneva go through with the peace talks.

For this reason, de Mistura said it was necessary for the US and Russia to step up efforts to restore the ceasefire that was largely holding weeks earlier. Both countries are active players in the region and support opposing sides of the conflict.

Russia on Tuesday proposed that the UN blacklist two Syrian rebel groups - Jaish al-Islam and Ahrar al-Sham - for links to Islamic militants such as the so-called "Islamic State" (IS).

Civilian deaths mount

Last week, the mainstream opposition alliance High Negotiations Committee (HNC), which represents the Western-backed rebels of Assad's regime, said it was suspending its particpation in the talks due to the civilian attacks.

Government forces under the control of President Bashar Assad carried out aerial bombardments on the northern city of Aleppo on Wednesday, killing at least 14 civilians.

Earlier, another series of air strikes killed at least 11 civilians, also in Aleppo.

blc/gsw (Reuters, AFP)