DUBAI - Hospitals in Bahrain, where the government has cracked down on protests and imposed martial law, have become places to be feared where wounds can identify people for arrest, a medical charity said Thursday. Bahrain has seen the worst sectarian clashes between its Shi'ite majority and the Sunni-ruled security forces since the 1990s after Shi'ite protesters, inspired by uprisings in Tunisia and Egypt, took to the streets in February. At least 13 protesters and four police have been killed. Bahrain's Sunni-led government has arrested activists, Shi'ites and bloggers and called in troops from Sunni-ruled neighbors, including Saudi Arabia, to help quell the protests. "Wounds, especially those inflicted by distinctive police and military gunfire, are used to identify people for arrest, and the denial of medical care is being used by Bahraini authorities to deter people from protesting," said Latifa Ayada, Medecins Sans Frontieres (MSF) medical coordinator. "Health facilities are used as bait to identify and arrest those who dare seek treatment," she said in a statement. Hospitals in Bahrain "no longer serve the medical needs of the whole population," MSF said. Salmaniya, the only public referral hospital in Bahrain, was almost empty when MSF visited it. Security forces occupied the hospital, the country's largest, on March 16, it said. "Injured people admitted to Salmaniya have told MSF how members of the military beat them, including on their wounds," MSF said. "Other patients have been arrested within health facilities upon discovery that their injuries are related to the protests. The risks of going to hospitals or health centers mean that patients often do not attempt to seek treatment."