Ban Phu Citadel, a national historic site and an attractive destination for visitors to the northern mountainous province of Dien Bien, has been seriously encroached by local people.

The citadel was built in the 18th century in Noong Het Commune, about 10km from Dien Bien Phu City, by Hoang Cong Chat (1706-69).He led peasants in a resistance movement against village tyrants, looters and invaders from the north.

The relics and temple nearby demonstrated the leader's merit to the country and people. The place was recognised as a national historic site in 1981.

Located to the south of Muong Thanh paddy field, the site, with its poetic scenery of lotus ponds surrounded by a garden of old trees grown by Chat as a symbol of solidarity, attracts thousands of visitors every year.

The annual festival commemorating the leader is organised on the 25th of the second lunar clendar month, his death anniversary.

However, in recent years, many people who live near the relics trespassed onto citadel land to live and work, according to Tran Cong Kha, chairman of the People's Committee in Noong Het Commune.

The structure of this citadel includes two systems of defence works which are about 5m high and several kilometres long, separating the inner citadel from the residential area.

The wall's base is surrounded by dense bamboos and a deep moat. Now many people use parts of the base and moat to grow bananas and raise fish. Walls of the citadel are sometimes converted into makeshift houses and stalls.

Worse still, some locals set up breeding facilities close to the site, causing pollution and inconveniencing tourists.

"The provincial Department of Culture, Sports and Tourism recently upgraded the infrastructure and widened the roads to make it more convenient for tourists and organising festivals," said Kha.

"We warned the people who trespassed in the corridor of the citadel that if they don't clear away illegal constructions up to 5m from the wall's base, we will co-operate with relevant agencies to coerce them," he said.