Ethnic minorities make up 15% of the population

Mr Rise, from Norway's opposition People's Party, was arrested as he walked out of a church building in Hue, where he was visiting a Catholic priest, Nguyen Van Ly. About 100 policemen had surrounded the church.

He had also met Thich Quang Do - a dissident Buddhist monk who was a Nobel Peace Prize nominee - in Ho Chi Minh City.

The two religious leaders are under house arrest after they criticised the authorities for imposing religious restrictions.

Church crackdown

A diplomat in Hanoi told Reuters news agency that Rise had come to Vietnam on a tourist visa, not with an official parliamentary delegation.

"In Vietnam's view he violated the law by coming as a tourist, then going to see persons under arrest," the diplomat said.

A decree has warned against complaints against the state

Human rights groups have criticised Vietnam for religious repression, citing the crackdown on Protestant "house churches" which have attracted many followers from ethnic hilltribes.

There have been reports that some churches were torn down by the authorities, provoking clashes between police and protesters.

New campaign

The new law awareness campaign in the Central Highlands, aimed at preventing further unrest among ethnic minorities, will see more than one million pamphlets being distributed to villages in Gia Lai province, officials said.

The government also provided the provinces with pictures of Vietnamese revolutionary leader Ho Chi Minh, to be distributed free.

The region was swept by huge protests involving thousands of people in February, in the capitals of Gia Lai - Pleiku - and Daklak provinces.

The protests were fuelled by anger over religious rights as well as the government turning ancestral forests into the country's largest coffee-growing region.