Another land dispute is raging at the Thai Ha parish of Hanoi
Tensions are high in the Vietnamese capital Hanoi, after the authorities began construction work on land claimed by the Catholic Church.
At dawn workers moved bulldozers past a police guard onto the disputed site at Nha Chung street.
Crowds of priests and believers soon gathered outside.
The site, which once served as the Vatican ambassador's residence, was at the centre of a month-long protest by Hanoi Catholics earlier this year.
They only learned that their claim to the land had been turned down the previous afternoon, when the authorities announced via the state media that it would become a park.
A witness told BBC that the police had sealed off the whole area to prevent people getting in.
"But we could see from outside that they have started digging the ground and clearing the front of the residence," she said.
Another witness said scores of riot policemen and sniffer dogs were mobilised and the whole scene looked "very chaotic".
Thousands of Catholics held prayers at the site for the whole of January as they pressed their claim to the land. They say the land was borrowed from the Apostolic delegation of the Hanoi Diocese and it is time to give it back.
The crowds only dispersed after the Archbishop of Hanoi told them that the government had promised to return the land.
Archbishop Ngo Quang Kiet has personally petitioned the government
However, eight months on and the authorities have decided to transform the former residence into "a green tree park with flower beds and grass lawns", reports the Ha Noi Moi newspaper.
"The event today caught us totally off-guard," said Father Nguyen Van Khai, spokesman for Archbishop Ngo Quang Kiet, adding that a protest has been quickly formed to "ask for justice".
The Archbishop himself has sent an urgent petition to the Vietnamese prime minister and president, asking them to intervene to stop "activities damaging to the Hanoi Diocese's assets".
Luu Van Dat, an official from the state-sponsored Fatherland Front, acknowledged that the ongoing dispute has escalated to a "serious" level.
He said: "The authorities should look into this matter. We have to be very careful in order to protect the rights [of citizens] but also to follow the law."
Meanwhile, the church has called on all believers to join in protests, as well as pray for the Catholic claim to more disputed land in Hanoi, this time at Thai Ha. This second land grievance has been going on for more than a month, attracting hundreds of believers for prayer and protest every day.
The Vietnamese government maintains that all land belongs to the state and land claims should be submitted to the law courts for consideration.