Tunisia will work in the United Nations and the Arab League to stop Israel's "flagrant aggression" in the Gaza Strip, Tunisian Foreign Minister Rafik Abdesslem said during a visit to the coastal enclave on Saturday.

"Israel should understand that many things have changed and that lots of water has run in the Arab river," Abdesslem said as he surveyed the office of Hamas Prime Minister Ismail Haniyeh reduced to rubble in an overnight air strike.

"[Israel] should realize it no longer has a free hand. It does not have total immunity and is not above international law," he added. "What Israel is doing is not legitimate and is not acceptable at all."

Israel launched a concerted air campaign against the densely populated territory on Wednesday with the stated aim of halting regular rocket fire out of Gaza that has disrupted life across southern Israel.

Palestinian militants have fired hundreds more rockets in the last three days, even targeting the far-away centers of Israeli commerce and government -- Tel Aviv and Jerusalem.

Abdesslem is the second high-profile visitor to Gaza since the start of the latest wave of violence, with Egyptian Prime Minister Hisham Kandil travelling to the territory on Friday.

Their appearance in the enclave reflects ever-stronger Arab solidarity with Gazans and their Islamist leaders following uprisings across the region, which have propelled Islamist-led governments to power in Egypt and Tunisia.

"The Arab League should bear its responsibilities to stop this flagrant aggression on our people in Gaza," Abdesslem said.

Officials in Gaza said 39 Palestinians, half of them civilians including eight children and a pregnant woman, had been killed since Israel began its air strikes. Three Israeli civilians were killed by a rocket on Thursday.