Japan began preparing to send a disaster relief team to Sri Lanka at the request of its government following massive tsunami damage from a powerful earthquake that struck off Indonesia's Sumatra Island, media reports said Sunday. The Japanese government set up an emergency office at the Foreign Ministry and began studying the dispatch of a medical unit to Sri Lanka, the Japanese news agency Kyodo reported. The medical unit is ready to leave Japan for the disaster areas within 48 hours after a request, officials were quoted as saying. According to the Japanese news agency Jiji Press, around 20 Japanese tourists are missing in the south of Thailand, one of seven nations on the Indian Ocean affected by the tidal waves.