HANOI (AFP) — Communist Vietnam's police Thursday arrested four Catholics who have taken part in mass prayer vigils this month for the return of church land taken in the 1950s, local Catholics said.

More than 100 followers later staged a peaceful protest outside a police station in Hanoi's Dong Da district after the arrests, which came as state media signalled authorities would move to end the church rallies.

"Four Catholics -- two men and two women -- were arrested this morning and they are now detained at Dong Da district police station," said one 22-year-old Catholic man whose comments were backed by other local church followers.

"Police are searching for more people to arrest, but we are determined to go all the way for the return of the disputed land," he told AFP.

Hundreds of Catholics this month staged mass prayer vigils on the land, part of the capital's Thai Ha parish until the mid-1950s when communists took power from the French in North Vietnam and seized most church land.

Vietnam's government has since used most of the Redemptorists' former six-hectare (15-acre) Hanoi property to build a hospital and industrial structures, including a textile factory that has since been demolished.

Vietnamese officials say the church donated the land to the Vietnamese communist state half a century ago, a claim the Catholics have denied.

On Thursday several dozen Catholics, mainly elderly women, maintained a vigil before a makeshift altar decorated with a cross and religious icons set up on the rubble-strewn lot where the textile factory formerly stood.

The state-run Vietnam News Agency (VNA) reported early Thursday that police had started "legal proceedings" against people involved in the dispute after Christians broke part of a wall and entered the property on August 15.

The head of the capital's Dong Da district police, Vu Cong Long, said investigators aimed "to bring to trial those who intentionally damaged property and provoked a disturbance of public order," the VNA report said.

The charges carry up to three years in jail for damaging or destroying property, and two to seven years for causing public disorder.

Hanoi authorities had also "asked relevant agencies to confiscate the whole acreage in dispute in Dong Da district for building public projects," VNA said.

Catholics first staged prayer vigils at the site in January, when thousands of faithful also flocked to a disputed property adjacent to the larger St Joseph's Cathedral and monastery compound in downtown Hanoi.

The daily protests at Hanoi's main cathedral only ended after official pledges to resolve the issue before the February Tet lunar New Year.

"This dispute has been going on for about 10 years, but it exploded eight months ago here," said the young Catholic man, speaking about the Dong Da row.

Vietnam, a unified communist country since the war ended in 1975, has Southeast Asia's largest Catholic community after the Philippines -- at least six million out of a population of 86 million.