Israel's air force carried out the largest daytime airstrike campaign against Hamas in the Gaza Strip since the 2014 war on Saturday, killing two teenagers in an escalation of violence in the region after months of deadly protests.

The Israeli air strikes came as Hamas intensified its attacks, firing dozens of mortar rounds at Israel on Friday night and throughout Saturday, some of which were intercepted by Israel's Iron Dome air defence system.

Witnesses said the Israeli air strike hit an empty building in Gaza City and the two casualties were passers-by. A further 15 Palestinians were also reported to have been injured, as well as three Israelis.

An Israeli government official said it had decided "to take strong action against Gaza aggression".

The escalation follows violent protests on the Gaza border on Friday in which two Palestinians were also killed - a 15-year-old and a 20-year old - and more than 220 injured, according to Gaza's health ministry. Israel said one of its soldiers was injured.