Patients in Syrian state hospitals are subjected to torture and mistreatment as part of the government's crackdown on dissent, while medics are also being targeted, Amnesty International said.
A leading Syrian rights activist, meanwhile, said the Damascus regime has detained more than 30,000 people since launching a deadly crackdown on opposition protests in March.
"The Syrian government has turned hospitals into instruments of repression in its efforts to crush opposition," London-based Amnesty said in a 39-page report released late on Monday.
The report documented how wounded patients in at least four government-run hospitals had been subjected to torture and other ill-treatment, both by medical workers and security personnel.
And "hospital workers suspected of treating protesters and others injured in unrest-related incidents have themselves faced arrest and torture," it said, leaving them in a dilemma.
"It is deeply alarming that the Syrian authorities seem to have given the security forces a free rein in hospitals, and that in many cases hospital staff appear to have taken part in torture and ill treatment of the very people they are supposed to care for," said Cilina Nasser, Amnesty International Middle East and North Africa researcher.
"Afraid of the consequences of going to a government hospital, many people have chosen to seek treatment either at private hospitals or at poorly equipped makeshift field hospitals," the report said.
"Syrian medical workers are being placed in an impossible situation -- forced to choose between treating wounded people and preserving their own safety," it said.
A crackdown on anti-regime protests in Syria since mid-March has left more than 3,000 dead, according to the United Nations.
Radwan Ziadeh, co-founder of the Damascus Centre for Human Rights, told a media conference at the UN headquarters in New York that nobody knew the exact figure for the number of detainees.
But based on reports of activists working underground in Syria, "we have an estimate number that more than 30,000 have been detained."
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President Bashar al-Assad's government has turned all the country's main football stadiums into prisons, Ziadeh said at the launch of the Observatory for the Protection of Human Rights Defenders' annual report.
"The Syrian regime actually cancelled the football championship because they turned over all the soccer fields to be detention centres and torture centres," said Ziadeh, who has been condemned by Syrian media close to the country's president.
He said that the UN Security Council's failure to pass a resolution on the Syria crisis had made opponents of Assad more desperate and more ready to use guns "to defend themselves against the security forces."
Russia and China vetoed a proposed European resolution on Syria, saying there should be no threat of sanctions against Assad.
Western powers again criticised the veto at a Security Council meeting on the Middle East on Monday.
France's UN ambassador Gerard Araud said those who vetoed the resolution or abstained must explain to the Syrian people and international opinion "what concrete action they propose to end this bloodbath."
"It is tragic that Assad’s barbaric acts have recently been met by silence from this council," added US ambassador Susan Rice.
The United States condemned the Syrian army's incursions into neighbouring Lebanon and suggested that dissidents had either been killed or taken prisoner at the border.
"Over the course of the last few weeks, it appears Syrian forces have entered Lebanese territory," a State Department spokesman told reporters in Washington.
"We are also deeply concerned by indications that Syrian dissidents may have been captured and possibly killed during operations near the border."
Syria on Monday recalled its ambassador to Washington, according to an official television station, shortly after the United States said it had pulled out its envoy from Damascus for safety reasons.
The State Department said ambassador Robert Ford, an open critic of Assad's crackdown on political dissent, had left Syria indefinitely after "credible threats" against his security.