Western countries including the United States blamed Syrian government forces for the attack, which choked scores of people to death in the town of Khan Sheikhoun in a rebel-held area of northern Syria hit by government air strikes. The Syrian army has denied any role.
"We look on horrified by the recent events in Syria," he told tens of thousands of people in St. Peter's Square for his weekly general audience.
Expressing his "firm deploration of the unacceptable massacre that took place yesterday," the leader of the world's 1.2 billion Roman Catholics said he was praying for "the defenceless victims, including many children."
Francis appealed to "the consciences of those who hold political power, both at the local and international levels so that these tragedies end."
Francis also condemned the bombing on Tuesday of the metro in St. Petersburg, Russia, which killed 14 people and wounded about 50 others.
(Reporting by Philip Pullella; Editing by Janet Lawrence)
(This story has not been edited by NDTV staff and is auto-generated from a syndicated feed.)
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