Tunisia's Foreign Minister Rafik Abdessalem (C) gestures as he visits the office building of Hamas Prime Minister Ismail Haniyeh that was destroyed by an Israeli air strike in Gaza City November 17, 2012. REUTERS/Mohammed Salem

Tel Aviv - Israel bombed the offices of Ismail Haniya, the prime minister of Hamas, in Gaza early Saturday in retaliation for Palestinian rocket attacks as the fighting entered its fourth day.

Haniya was not in his office when it was hit.

Palestinian militants launched between 15 to 20 rockets at southern Israel early Saturday.

An Israeli military spokeswoman said that in addition to Haniya's offices, Israel also bombed the Hamas-run Interior Ministry, a police compound in Gaza City, more than 100 rocket launchers, and tunnels under the border with the Sinai Peninsula that are used for smuggling.

There was no immediate confirmation of Palestinian and Israeli casualties from the latest attacks.

By midnight (2200 GMT), the combined death toll was 32: 29 Palestinians, including at least 12 civilians, and three Israeli civilians.

The Israeli military said Saturday that since Operation Pillar of Defence started, it has struck more than 800 targets in the Gaza Strip. More than 350 rockets, and not 390 rockets as said earlier, had landed in Israel, the military confirmed.

Israel began the offensive Wednesday with an airstrike that killed the head of Hamas' military wing, Ahmed Ja'abari. It was approved after days of incessant rocket attacks on southern Israel by Islamic Jihad, Hamas and other armed groups.

On Friday, Israeli Defence Minister Ehud Barak approved a military request to increase the number of reservists it could mobilize.

Media reports gave the number of reservists liable for call up as 75 000. It remained unclear whether Israel would expand its operation by sending ground troops into the Gaza Strip. - Sapa-dpa