JERUSALEM: Rocket attacks carried out against Israel by the Hamas rulers of Gaza and other Palestinian militants amount to war crimes, Human Rights Watch said in a report published on Thursday.

"Hamas forces violated the laws of war both by firing rockets deliberately and indiscriminately at Israeli cities and by launching them from populated areas and endangering Gazan civilians," HRW programme director Iain Levine said.

"Hamas rocket attacks targeting Israeli civilians are unlawful and unjustifiable and amount to war crimes," he said.

The 31-page report examines attacks by Hamas and other Palestinian armed groups since November 2008 that killed three Israeli civilians and severely wounded dozens of others.

The homemade Qassam and Soviet-designed Grad rockets used by Palestinian groups in the Gaza Strip cannot be aimed with any reliability, the report says.

"Under the laws of war, such weapons are indiscriminate when used against targets in densely populated areas," the New York-based watchdog said.

"As the governing authority in Gaza, Hamas should publicly renounce rocket attacks on Israeli civilian centres and punish those responsible, including members of its own armed wing," Levine said.

Israel cited persistent rocket fire from Gaza as its reason for launching a devastating December 28-January 18 offensive that killed more than 1,400 Palestinians.

HRW noted that in the past it had documented numerous violations of the laws of war by Israeli forces in Gaza, but stressed that "violations by one party to a conflict never justify violations by the other."

It said Hamas has "significantly limited rocket attacks in recent months, but has not renounced attacks that deliberately or indiscriminately target civilians -- serious violations of the laws of war -- or brought to justice those responsible for initiating such attacks."

The Israeli military is conducting 15 criminal probes into troop conduct during the offensive, including allegations children were used as human shields.

But the Israeli foreign ministry has said that so far the evidence shows the troops "pursued legitimate objectives with appropriate precautions," while Hamas committed "grave violations of international law."