HRW said Israel's contention that Hezbollah fighters were hiding among Lebanese civilians did not justify its "systematic failure" to distinguish between civilians and combatants.

"In some instances, Israeli forces appear to have deliberately targeted civilians," HRW said in a statement accompanying a report released on Thursday.

"The failures cannot be dismissed as mere accidents and cannot be blamed on wrongful Hezbollah practices. In some cases, these attacks constitute war crimes."

At least 646 Lebanese, mostly civilians, have died in the strikes. The mounting toll, compounded by Sunday's bombing of the Lebanese village of Qana in which 54 civilians died, has fueled international outcry against Israel's tactics in the three-week-old war.

Israel says its strikes destroy Hezbollah infrastructure and stop rocket attacks that have killed 56 and caused large-scale evacuations in Israel.

HRW Executive Director Kenneth Roth said in the many cases of civilian Lebanese deaths investigated by the rights group, the location of Hezbollah members or their weapons stores appeared to have no bearing on the areas attacked.