Sri Lankan troops launched an all-out offensive against Tamil rebels in the northern Jaffna Peninsula, and the government reported that at least 20 guerrillas and five soldiers were killed. A Tamil group reported more than 100 civilians killed, most by air raids. Sources in Colombo, the capital, said that as many as 50 wounded soldiers were being airlifted from the scene of the fighting, about 185 miles to the north. Tamil rebels have controlled the peninsula for two years. Tamils, most of whom are Hindus, form 18% of the island's population of 16 million, and they claim discrimination by the Buddhist Sinhalese majority.