Half of Croatian high school pupils think homosexuality is an illness and two-thirds say gay rights marches should be banned, a poll said Friday. Some 47 percent of final year school students polled said \"homosexuality is illness,\" the survey done by non-government rights group GONG found. More than 64 percent of the 999 respondents in 43 schools said gay pride parades should be banned as they \"have a harmful effect on education of young people,\" the poll showed. On June 11, a gay pride parade in the coastal town Split was marred by violence when anti-gay protestors pelted marchers with stones and bottles, injuring about a dozen people, four of them journalists. A week later, another parade was held without incident in the capital Zagreb. Croatia\'s first gay pride parade was held in Zagreb in 2002, with more than a dozen participants beaten up afterwards. Since then, parades have been held in the capital annually without major incidents, but always under heavy security. Croatian society is largely conservative and the influential Roman Catholic Church has publicly branded homosexuality a \"handicap\" and a \"perversion\". Almost 88 percent of the former Yugoslav republic\'s population of 4.4 million are Roman Catholics.