Lebanese health minister says the death toll from an Israeli airstrike on a Beirut suburb the day before has risen to 31, including seven women and three children.

Israel and Lebanon exchanged heavy fire into Sunday, with Israeli warplanes carrying out the most intense bombardment in almost a year of war across Lebanon's south, while Hezbollah claimed rocket attacks on military targets in Israel's north.

At least 22 people, mostly women and children, have been killed in an Israeli strike on a school compound Saturday, Palestinian officials said, with Israel saying it targeted Hamas fighters sheltering there.