Israeli planes blitzed Qana early Sunday, killing at least 52 people, including 30 children. It was the single most deadly incident in the 19-day-old offensive, originally triggered by the kidnapping of two Israeli soldiers by Hezbollah militants.

Israel has halted its airstrikes for 48 hours pending an investigation.

Indonesia, the world's most populous Muslim nation, branded Israel's attack a criminal act that violated international and humanitarian laws.

"The Indonesian government strongly condemns this criminal act, which goes beyond humanity," a government statement read by foreign affairs spokesman Desra Percaya said.

Indonesia, which does not have diplomatic ties with Israel, urged the UN Security Council to enforce an unconditional ceasefire. The 15-member body has said it "strongly deplores" the deaths and called for an end to the violence.

Pakistan also denounced the attack as thousands of its Muslims protested.

"Pakistani government and people strongly condemn this sad incident, which is clearly unwarranted aggression," Prime Minister Shaukat Aziz told reporters on Sunday.

He appealed to the world community to come forward and help find "an immediate and peaceful settlement" to the conflict.

Around 3,000 people braved rain to rally in the port city of Karachi over the attack, vowing to support the Lebanese people. The minority Shia Muslim community also held a separate rally in Karachi attended by more than 1,000 people.

The call for a ceasefire was echoed in Afghanistan, where foreign ministry spokesman Sultan Ahmad Baheen said Kabul "strongly condemned" the latest attack.

"We want an end to the fighting. We want an urgent ceasefire," he said.

The outrage reverberated right across Asia.

China said it strongly condemned the attack as it pushed for a ceasefire.

"China strongly urges the two sides involved in the conflict to cease fire immediately to avoid further disaster," Xinhua news agency quoted foreign ministry spokesman Liu Jianchao as saying.

In Japan, the government's top spokesman Shinzo Abe said it was "extremely regrettable that this kind of incident occurred amid international calls on Israel to exercise self-restraint," according to Kyodo News. Tokyo also called on both sides to implement a ceasefire.

Singapore said it was "deeply shocked and saddened by the loss of innocent lives" as it too backed the UN call, saying it would be "an important first step to pave the way for a solution that would secure security for all parties and peace and stability in the region."

India labelled the air raid "outrageous" and added its voice to the chorus of calls for an unconditional ceasefire, along with Thailand, which said it was "deeply shocked".