Bombing hospitals and targeting health-care workers has become "an actual strategy of war" in Syria, human rights groups say.

"It is truly alarming," Susannah Sirkin, director of international policy and partnerships with Physicians for Human Rights, told CBC News. "We have never seen [this] degree and severity in terms of both quantity and kind of attack on hospitals."

Susannah Sirkin of Physicians for Human Rights says a 'grotesque practice' known as 'double tapping', in which a hospital is bombed twice so medics rushing to respond are also hit, has become common in Syria. (Physicians for Human Rights)

Both Syria and Russia, blamed for most of the incidents, have denied targeting hospitals and health-care workers.

According to the advocacy group, which has been investigating and documenting the attacks, more than 730 medical workers have been killed and more than 350 medical facilities have been attacked since the start of the Syrian conflict in 2011 through the end of March 2016.

Those numbers do not include dozens more casualties from the most recent bombings of two hospitals in Aleppo at the end of April and beginning of May. A Canadian-supported medical clinic was also destroyed at the end of April, but no one was inside at the time it was bombed.

Physicians for Human Rights says its research indicates the vast majority of the attacks — "more than 90 per cent" —were carried out by "Syrian government forces and their Russian allies."

Armed opposition and rebel forces have carried out about a dozen attacks on medical facilities, according to the group's data. The Islamic State in Iraq and Syria (ISIS) was responsible for at least eight attacks on medical facilities and for killing more than a dozen medical staff.

'Grotesque practice'

Diederik Lohman, interim director of health and human rights for Human Rights Watch, said there have been attacks on health facilities in other countries, including Yemen and South Sudan, but the war in Syria has marked a "real shift" away from compliance with international laws protecting health care workers and the neutral role they play.

The Syria conflict has 'really eroded respect' for international laws protecting health-care workers and their neutrality in war, says Diederik Lohman of Human Rights Watch. (Human Rights Watch)

"The Syria conflict has really eroded respect for the rule," Lohman told CBC News, noting that the United Nations Security Council's unanimous adoption of a resolution on May 3 condemning attacks on health-care centres sent the important message that "this is not normal" and "explicitly prohibited by international law."

Amnesty International also has highlighted the trend of hospital bombings, issuing a report in March that accused Russian and Syrian forces of targeting medical centres.

Both Lohman and Sirkin said it's hard to produce absolute proof the Syrian and Russian governments are ordering their pilots to target hospitals in airstrikes because there's no paper trail. But the sheer number and pattern of attacks leads to a logical conclusion that the destruction of health-care facilities during bombings is intentional, they said.

Marianne Gasser, head of the International Committee of the Red Cross (ICRC) in Syria, condemned the "appalling acts of violence deliberately targeting hospitals and clinics" in a news release issued at the end of April after attacks on medical facilities in Aleppo. The ICRC said the clinics were on "both sides of the frontlines."

Damascus and Moscow have both denied accusations that they carried out the April strike on the al-Qudos hospital in Aleppo that killed 30 people. Both said their airplanes were not involved in the bombing, claiming to have detected aircraft from an anti-Islamic State coalition.

But even if the hospitals hadn't been explicitly targeted but were hit during bombings of the area around them, Lohman said, that could still constitute a war crime due to negligence or recklessness.

Sirkin pointed to a "grotesque practice" known to Syrian medics as "double tapping" as evidence attacks are likely intentional. It has become common, she said, for an airstrike to bomb a hospital once, then again after first responders have arrived on the scene to take care of people injured in the first attack.

"You can only infer that they are aiming to kill the maximum number of hospital workers and patients in these double-tap attacks," Sirkin said.

'Impossible to live' when health services gone

Attacking hospitals and health-care workers is used as a war strategy in Syria, she said, because in the division between pro-government forces and opposition groups, as well as other parties like ISIS, "the entire population and its infrastructure is considered to be the enemy."

"[There is] certainly the notion that ... the doctor who treats my enemy must be my enemy," Sirkin said. "The idea appears to be, you kill a doctor to intimidate them and their patients to cause people to flee, to destroy their ability to treat the injured and wounded."

As this "strategy of war" continues, she said, the perpetrators destroy entire communities by eliminating health services, as well as the people who provide them.

"You're emptying out hospitals, you're making people afraid to go to the hospital for treatment, so they get sick or die elsewhere. You force doctors who are leaders of communities ... to flee," Sirkin said.

People living in conflict zones are already vulnerable to illness because of crumbling infrastructure and disruptions to food and water supply, as well as the threat of injury from the war itself, Lohman said.

If health services are destroyed on top of that, he said, "you essentially make it ... impossible to live."