Opposition groups in Syria have agreed a two to three week ceasefire if Russia agrees to stop its airstrikes.

The agreement would be renewable and supported by all parties in the conflict with the exception of the so-called Islamic State, a source close to the peace talks has told Reuters.

Russian airstrikes begun last September supporting President Bashar al-Assad's forces after months of military gains by opposition forces.

Peace talks in recent weeks had failed to secure a complete ceasefire or end Russian bombing in the country.