Hand-held radios used by armed group Hezbollah detonated on Wednesday across Lebanon's south in the country's deadliest day since cross-border fighting erupted between the militants and Israel nearly a year ago, stoking tensions after similar explosions of the group's pagers the day before.

Lebanon's health ministry said 20 people were killed and more than 450 injured on Wednesday in Beirut's suburbs and the Bekaa Valley, while the death toll from Tuesday's explosions rose to 12, including two children, with nearly 3,000 injured.

Israeli officials have not commented on the blasts. The attacks, however, coincided with an announcement by Israeli Defense Minister Yoav Gallant of a "new phase" in the conflict with Hezbollah.