Foreign Ministry spokeswoman Nguyen Phuong Nga's statement Thursday is Vietnam's first acknowledgment of arrests in the incident. Nga did not say how many were detained or whether there were deaths or injuries as has been alleged by overseas Hmong groups.

Officials in northwest Dien Bien province have accused overseas groups of using the incident to influence some Hmong to call for an independent state.

Vietnam has not granted foreign journalists or diplomats access to the area since security forces broke up the gathering in Muong Nhe district in early May. Nga said the Hmong have all returned home.

U.S.-based Human Rights Watch has called for a full investigation and for journalists and diplomats to be allowed access.

Up to 5,000 Hmong had gathered in the district town to await for God, expected to take them to the promised land on May 21.

There is a long history of mistrust between the government and many ethnic hilltribe groups, collectively known as Montagnards. Many anti-communist hilltribe fighters were allied with the United States during the Vietnam War, and many Hmong refugees resettled there after the war.

The Associated Press - May 13, 2011