Jerusalem - There is mounting evidence that Israeli ambulance crews are withholding treatment from Palestinians injured during a wave of attacks over the past six months, according to rights groups.

Physicians for Human Rights in Israel, a medical watchdog group, found that wounded Palestinians had been left untreated for as long as two hours.

In some cases, medical teams are suspected of failing to tend to the injuries of suspected attackers as revenge, in the expectation that they will die from their wounds.

In parallel, says the group, Israeli soldiers regularly deny Palestinian crews in the occupied territories access to injured Palestinians in violation of international agreements. Palestinian ambulances have been regularly fired on and paramedics attacked as they tried to reach the scene.

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Physicians for Human Rights accused Israel's leading medical bodies - the Israeli Medical Association, which lays down ethical codes, and Magen David Adom, which supervises ambulance services - of ignoring the evidence it has collected of such abuses.

Israel should be removed from the [International Committee of the] Red Cross for these violations until it is prepared to follow internationally accepted codes of conduct. Mustafa Barghouti, Palestinian politician and physician

"We have seen no serious response to our complaints, no investigations, not even an attempt to meet us. They don't appear to want to give answers," Mor Efrat, a researcher for the rights group, told Al-Jazeera.

Concern that some ambulance crews are adopting a policy of denying Palestinians treatment has been heightened by the increasing role of medical teams located in illegal Jewish settlements.

These paramedics appear to be openly flouting internationally established principles of neutrality that all medical staff are supposed to observe.

In December the leaders of United Hatzalah, a settler ambulance service implicated in several cases in which Palestinians have been refused treatment, visited a leading ultra-Orthodox rabbi, Chaim Kanievsky, to receive instructions on what to do with Palestinians injured during attacks.

According to a report on the settlers' website Israel National News, Kanievsky told them that if the injured Palestinian "was in a life-threatening condition, they should leave him or her to die". Other rabbis have made similar calls.

The issue of Israel's treatment of injured Palestinians was thrust into the spotlight late last month when a soldier from the Israeli army's medical corps was caught on video executing a badly injured Palestinian in the West Bank city of Hebron.

Abdel Fattah al-Sharif, aged 21, had been shot and wounded during a suspected knife attack on a checkpoint. Before the medical corps soldier, identified as Sergeant Elor Azaria, executed him by firing a bullet into his head, al-Sharif was left bleeding on the ground for more than 10 minutes.

Both army medics and two civilian ambulance teams, one of them United Hatzalah, refused to treat him. After the video was publicised, Sgt Azaria was arrested.

On Monday, an Israeli military court charged the soldier with manslaughter and inappropriate military conduct. However, there has been an outpouring of support for him, from the Israeli public, politicians and rabbis. Efrat, of Physicians for Human Rights, said the failure by both the Israeli Medical Association and Magen David Adom to speak out against abuses committed by Israeli medical staff created the climate that made possible the events in Hebron.

Leonid Eidelman, head of the Israeli Medical Association, told Al-Jazeera the criticisms were "unfair" and that his organisation had "stated clearly that no political or personal preferences should influence treatment" of wounded Palestinians.

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The criticisms of ambulance crews follow a heated debate among Israel's medical authorities about whether staff should abide by the Geneva Conventions, which require them to remain neutral at all times and prioritise treatment based solely on the severity of injuries.

ZAKA, an Israeli organisation of community medical volunteers, has backed members who refuse to treat Palestinians before Israeli Jews. By contrast, Eli Bein, the head of the Magen David Adom, has said he expects ambulance staff to follow international humanitarian law.

Nonetheless, Magen David Adom has justified the failure of its paramedics to treat al-Sharif in Hebron last month, claiming they were waiting for authorisation from the Israeli army.

Army commanders told the Haaretz newspaper the claim was unfounded and was being used as a "pretext for delaying treatment". The stance of the Israeli Medical Association has been equally ambivalent, according to critics.

In 2008 the Association adopted an ethical code - based on a Talmudic injunction that "Charity begins at home" - to treat Israelis before Palestinians. Under pressure from Physicians for Human Rights, the code was quietly revoked in December.

Doctors told the Times of Israel website that the Association was afraid of a political backlash if it publicised the change. "Whatever their official positions, these bodies are not speaking out clearly against violations of medical ethics. And they are certainly not taking any action," Efrat said.

In addition to last month's incident in Hebron, Physicians for Human Rights have highlighted several other clear cases of medical violations. One of the most disturbing relates to 19-year-old Muhannad Halabi, who was shot during an attack in the Old City of Jerusalem last October. Witnesses, including an Israeli medic, told the watchdog group that Halabi was left untreated for two hours before paramedics pronounced him dead.

Israeli soldiers fired stun grenades at a Palestinian crew that tried to reach him. A request from Physicians for Human Rights to Israel's justice ministry to investigate the incident has gone unanswered.

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In a second incident, a week later in the Old City, a video shows Palestinian paramedics being beaten and pushed away as they try to reach Basel Sidr, aged 19. Their medical equipment was also damaged. Witnesses said an Israeli ambulance crew looked on for 20 minutes before a medic approached Sidr to check his pulse and declare him dead.

In another video, paramedics are shown denying treatment to Sa'ad al-Atrash, who was shot at least six times last October by soldiers at a checkpoint in Hebron. Witnesses say he was left for half an hour lying in the street before being evacuated to hospital, where he died of his wounds. There are strong suspicions that al-Atrash was shot by a trigger-happy soldier, in what Amnesty International called an "especially egregious" example of unlawful killing.

In another case, last November, 21-year-old Mohammed al-Shawbaki was left untreated by three Israeli ambulance crews for 30 minutes, while a Palestinian crew was blocked from approaching.

Efrat said they had also filed complaints to the Israeli police and army about 18 incidents in the past six months where Palestinian medical teams had been prevented from caring for the wounded. Only one investigation had been opened.

Euro-Med Monitor, an international human rights group based in Geneva, has collected evidence of a further four cases where Israeli paramedics violated the Geneva Conventions by denying Palestinians treatment.

They include Ahmed Manasreh, a 13-year-old Palestinian accused of a stabbing attack in East Jerusalem last October. Videos show a Magen David Adom ambulance driving past Manasreh as he lies bleeding in the street, having earlier been run down by an Israeli vehicle.

Evidence of denial of treatment is likely to add to the pressure on two global organisations - the World Medical Association, and the International Committee of the Red Cross - to investigate the actions of their Israeli partner organisations.

A group of UK doctors launched a campaign earlier this year demanding that the World Medical Association expel the Israeli Medical Association for failing to act against Israeli doctors involved in the torture of Palestinians.

A number of reports by human rights groups suggest that, in violation of medical ethics, Israeli doctors are treating Palestinians who have been tortured in Israel's prisons and interrogation centres. The documented abuses range from physical and sexual assaults.

A spokesman for the World Medical Association told Al-Jazeera it was not aware of the new allegations and would be discussing them with the Israeli Medical Association.

The International Committee of the Red Cross said Magen David Adom was an "independent" emergency service and any issues would be "addressed internally" by the movement.

Mustafa Barghouti, a Palestinian politician and physician, said there was overwhelming evidence that Israeli ambulance crews were "consistently and systematically" denying treatment to wounded Palestinians.

"Israel should be removed from the [International Committee of the] Red Cross for these violations until it is prepared to follow internationally accepted codes of conduct," said Barghouti.