"We are talking about the biggest offensive strikes since Protective Edge," Brigadier General Tzvika Haimovic told journalists, referring to Israel's name for its 2014 operation in the Gaza Strip.

He said the "massive" air campaign was continuing. He could not give a precise figure of targets so far.

According to Haimovic, around 100 rockets and mortars have been fired from the Gaza Strip by Hamas and other groups, a number of which were intercepted by Israel's air defence systems. Most of the projectiles were mortars, he said.

Three Israelis were wounded from rocket fire that hit a house in Sderot near the Gaza Strip, authorities said.

"We are ready for all the scenarios that could be possible," Haimovic said.