Palestinian factions have fired barrages of rockets into Israel amid tension following Israeli air strikes on besieged Gaza.

In a statement on Wednesday, the factions said that the rocket fire was in response to the "assassination crime" of three Islamic Jihad leaders. "The resistance is ready to all options," the Palestinian factions added.

At least 21 Palestinians were killed and 64 others injured in a series of Israeli air strikes on occupied Gaza, according to the Health Ministry. Three leaders of Islamic Jihad group, their wives and children were among those killed in the attacks.

An Israeli military statement said that 270 rockets were fired from occupied Gaza, of which 205 crossed into Israeli territories.

According to the statement, 62 rockets were intercepted by its air defence systems while three fell into populated areas.

The Israeli army said 53 targets were struck in Gaza since the start of its offensive early on Tuesday.

The Israeli army said its air strikes on Gaza were part of its Operation Shield and Arrow in response to rocket fire from Gaza following the death of a Palestinian hunger striker in an Israeli prison last week.

According to Palestinian figures, at least 130 Palestinians have been killed by Israeli fire since the start of this year. Nineteen Israelis have also been killed in separate attacks during the same period.