Rights Groups Accuse Turkish Police of Excessive Force Against Protesters Turkish riot squads fired enormous amounts of tear gas, often at close range in confined spaces, and used other types of disproportionate force in their tactics to crush the antigovernment protests that erupted last month in Istanbul, Ankara and other cities, an alliance of international medical rights groups said in a report released Friday. The report, which cast a new light on the behavior of the Turkish police, expressed concern about what it called deliberate attacks on medical workers who had been aiding stricken protesters. The report also criticized what it described as unlawful detentions of individuals, including a prominent physician who is secretary general of the Istanbul Chamber of Medicine. "Our investigation in Turkey confirmed that the government has been engaged in the excessive and unnecessary use of force - including using tear gas as a weapon of mass scale - which has claimed several lives and led to thousands of injuries," Dr. Vincent Iacopino, the senior medical adviser to the Physicians for Human Rights, a Boston-based group that participated in the research and publication of the report, said in a statement on its Web site. Dr. Iacopino and other investigators returned from Turkey last week after interviewing more than 30 health professionals, victims and witnesses to the police attacks on demonstrators. Physicians for Human Rights and its partners, the World Medical Association, the German Medical Association and the Standing Committee of European Doctors, also released a letter they had sent Friday to Prime Minister Recep Tayyip Erdogan, asking his government to end such police behavior and to ban all use of tear gas, which they said had been fired "with devastating health consequences." The rights groups cited evidence compiled by the Turkish Medical Association that documented more than 8,000 injuries attributed to tear gas, rubber bullets, water cannons, beatings and live ammunition. Four people died in the mayhem, and 11 victims who were struck by tear-gas canisters lost eyes. Mr. Erdogan's office had no comment on the report and did not acknowledge receipt of the letter. But his government has defended what it has called the right of the police to use tear gas and water cannons against protests by groups that undermine public order. The protests initially grew out of peaceful demonstrations against a government-backed plan to raze Gezi Park, a section of Taksim Square in central Istanbul. The strong police crackdown on those demonstrations spawned widespread anger in Turkey and quickly morphed into broader protests against what Mr. Erdogan's critics called his arrogant and autocratic governing style. Sebnem Arsu contributed reporting from Istanbul.