A number of Syrian opposition groups have declared that they agree to the "possibility" of a temporary truce if Bashar al-Assad's regime and its allies respect several conditions, including halting fire.

The groups said on Saturday they would agree provided there were guarantees that the Syrian regime forces and its allies would respect a ceasefire, sieges were lifted and aid deliveries permitted across the country.

The announcement came as fighting continued on the ground despite a Friday deadline for cessation of hostilities.

Russian fighter jets are repeatedly striking Syrians, particularly in Aleppo, backing regime forces as they push towards Syria's second city.

The opposition factions "expressed agreement on the possibility of reaching a temporary truce deal, to be reached through international mediation", a statement from the High Negotiations Committee said.

It said the UN must guarantee "holding Russia and Iran and sectarian militias ... to a halt to fighting".

All sides should cease fire simultaneously and the regime should release prisoners, the statement said.

The UN is struggling to deliver aid to about 4.5 million Syrians who live in hard-to-reach areas, including nearly 400,000 people in besieged areas.

The fighting in Syria started as an unarmed uprising against Assad in March 2011.

Bombing campaign

Russia is currently flying a bombing campaign in Syria to back up forces loyal to Assad, while the US is leading a coalition against ISIL, which has seized territory in Syria and Iraq.

Syrian regime forces have also advanced in Aleppo province, backed by Russian air strikes.

PHOTO CAPTION

A child navigates rubble and barbed wire in Aleppo, Syria, Thursday, Feb. 11, 2016.

Al-Jazeera