Rocket attacks carried out against Israel by Hamas and other Palestinian militants amount to war crimes, Human Rights Watch (HRW) says.

Hamas rocket attacks targeting Israeli civilians are unlawful and unjustifiable, and amount to war crimes,” HRW says in a new report published on Thursday. The watchdog says Hamas should hold those responsible for them to account.

The 31-page report, ‘Rockets from Gaza: Harm to Civilians from Palestinian Armed Groups' Rocket Attacks,’ documents attacks by Hamas and other Palestinian armed groups since November 2008 that killed three Israeli civilians and severely wounded dozens of others.

Hamas and other Palestinian militants have launched thousands of rockets at Israeli cities and towns in the past years, including hundreds during Israel's three-week military offensive in Gaza in December 2008 and January 2009.

"Hamas forces violated the laws of war both by firing rockets deliberately or indiscriminately at Israeli cities and by launching them from populated areas and endangering Gazan civilians," the report says.

The handmade made Qassam rockets and Soviet-designed Grad rockets used by Hamas cannot be aimed with any reliability.

Under the laws of war, such weapons are indiscriminate when used against targets in densely populated areas. And individuals who wilfully authorise or carry out deliberate or indiscriminate attacks against civilians are committing war crimes, the New York-based watchdog says.

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 "violations by one party to a conflict never justify violations by the other."

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

A UN fact-finding investigation into serious violations of the laws of war by both sides in the Gaza conflict, led by Judge Richard Goldstone, is due to report back to the UN Human Rights Council in September.

(Photo: Human Rights Watch/Getty Images)