Pope Francis has decried the bombing of Aleppo in Syria, saying those responsible for killing civilians will have to answer to God. <br/><br/>Speaking at his public audience in St Peter's Square in Rome, he called it an already martyred city, where everybody is dying.<br/><br/>Russian-backed Syrian government forces have launched a fierce campaign to take back rebel-held parts of Aleppo. Airstrikes continued to hit the besieged northern city overnight. Pope Francis urged all sides to commit themselves with all their strength to protect civilians.