BANGKOK (AP) — A prominent Christian church leader and human rights advocate from Myanmar’s Kachin ethnic minority was detained by the authorities just hours after he was released from prison under an amnesty by the military government, a relative, a colleague and local media said Thursday.

The Rev. Hkalam Samson, former head of the Kachin Baptist Convention and chairman of the Kachin National Consultative Assembly, was among the 3,300 prisoners released nationwide on Wednesday to mark the traditional Thingyan New Year holiday. The assembly is an umbrella organization uniting religious and civil society groups with political organizations promoting Kachin rights, including autonomy from Myanmar’s central government.

Kachin state, in northern Myanmar, has been the scene of intermittent warfare for decades between the army and well-organized and -armed Kachin guerrillas.