UN Secretary-General Antonio Guterres said on Saturday that he condemned the "serious escalation" by Iran and called on all sides to show restraint to avoid a devastating regional conflagration.

"I am deeply alarmed about the very real danger of a devastating region-wide escalation. I urge all parties to exercise maximum restraint to avoid any action that could lead to major military confrontations on multiple fronts in the Middle East," Guterres said in a statement.