Israeli and Palestinian human rights groups said Monday they have collected evidence that Israeli troops attacked Palestinian medical workers and delayed the evacuation of wounded people during the recent offensive in Gaza.

The Israeli branch of Physicians for Human Rights, along with the Palestinian Medical Relief Society, called for an independent investigation. The groups said they collected evidence from 44 people in Gaza. The testimonies were gathered by five international medical experts commissioned by the groups.

Monday's report was the latest in a string of allegations by rights groups that Israel violated the laws of war during its offensive in Gaza. Israel launched the three-week operation in December with the goal of ending years of Palestinian rocket attacks and dealing a tough blow to the Islamic Hamas rulers of Gaza.

Palestinian human rights groups say more than 1,400 people were killed during the operation, including more than 900 civilians.

The Israeli military says the death toll was lower and that most of the dead were militants. It has blamed Hamas for civilian casualties, saying the militant group used residential areas for cover during the fighting.

Hadas Ziv, director of Physicians for Human Rights-Israel, said an independent investigation is needed to guarantee impartiality. "Since the Israeli army is incapable of holding such an investigation, we call for an international one," she said.

A recent army investigation into soldiers' accounts of wartime abuses found no wrongdoing and said the allegations were exaggerated and based on hearsay.

In a statement, the military said it could not respond directly to the report's allegations because it had not had time to investigate them.

But it said that the army "operates in accordance with international and Israeli law as well as all binding rules regarding the protection of medical personnel and facilities."

It said it took "multiple measures" to avoid harming medical workers, even though Hamas used hospitals and ambulances to carry out attacks. Nonetheless, it said an investigation ordered by the military chief is looking at "allegations made regarding harm caused to medical facilities and vehicles."