UN Secretary-General António Guterres has condemned an explosion in Lebanon in which three UN observers and a Lebanese language assistant were injured. The United Nations Interim Force in Lebanon (UNIFIL) is investigating the incident, the Secretary-General’s spokesman announced on Saturday in New York. The security of the peacekeeping mission must be guaranteed at all times, Guterres said. Such attacks are also a serious threat to the security and stability of Lebanon, Israel and the region he said. According to UNIFIL, the group had been on foot patrol along the Blue Line – the border with I…