Lao authorities are searching for the leader of a drug trafficking ring after uncovering 257 kilograms of marijuana in a house in the centre of the country, dpa quoted news reports as saying Friday. Authorities were tipped off to the haul, allegedly destined for export, and arrested four men at a house in olikhamxai province, the Vientiane Times reported. \"The four people we arrested Monday are not the most important members of the group. The leader was not there the day we broke up the operation,\" a police officer who participated in the raid told the daily.