SINGAPORE, Sept 15 (Reuters) - Asia's tiger population could be close to extinction with fewer than 3,500 tigers remaining in the wild and most clustered in fragmented areas making up less than 7 percent of their former range in Asia, a study says. The study in the latest issue of the online journal PLoS Biology says saving tigers living in 42 sites across Asia from poachers, illegal loggers and the wildlife trade is crucial to prevent the species becoming extinct in the wild. The cost of achieving this would be an additional $35 million a year in funding for law enforcement and monitoring, the report's lead authors from the U.S.-based Wildlife Conservation Society say. The World Bank, global conservation organisation IUCN and Panthera, a big cat environmental group, also contributed to the study. "The tiger is facing its last stand as a species," John Robinson, executive vice president of conservation and science for the Wildlife Conservation Society, said in a statement. Of the tigers remaining in the wild, only about 1,000 are breeding females. The authors said in spite of decades of efforts by conservationists, much of the decline was being driven by demand for tiger body parts used in traditional medicine. Overhunting of prey and destruction of hunting grounds were other reasons.