BANGKOK — A hydroelectric dam has collapsed in southeastern Laos, leaving several people confirmed dead and hundreds missing, according to state media.

The official KPL news agency reported Tuesday that the Xepian-Xe Nam Noy hydropower dam in Attapeu province collapsed Monday night, releasing large amounts of water and sweeping away houses, leaving more than 6,600 people homeless.

The dam was constructed by a joint venture led by South Korean companies, with Thai and Lao partners. It was scheduled to open this year, but it was unclear if it had begun operating.

KPL described the portion that collapsed as a "saddle dam," which is an auxiliary dam used to hold water beyond what is held by the main dam.

Communist Laos, one of Asia's poorest countries, is land-locked and aims to become the "battery of Asia" by selling power to its neighbors through a series of hydropower dams.

Environmental rights groups have raised concerns about Laos' hydropower ambitions for years, including worries over the impact of dams on the Mekong River, its flora and fauna and the rural communities and local economies that depend on it.