Vietnam has issued an official warning to four top priests at a Hanoi church that has been embroiled in a bitter land dispute with the local government.
The move followed a similar warning sent a day earlier to the city's archbishop, Ngo Quang Kiet, threatening to take legal action against him.
The archbishop and priests are accused of "stirring the population" and encouraging illegal religious activity.
Many Roman Catholics have been involved in prayer vigils over the issue.
The vigils have attracted a lot of attention from the public in Vietnam, as well as Vietnamese communities overseas.
The four priests who received the warning on Monday are from the Thai Ha parish, an area of which the authorities have decided to confiscate and transform into a park.
On Monday scores of people entered the disputed land and, after a short scuffle with believers holding a vigil there, drove them away.
Vietnamese state media said the newcomers represented "local people" who had sought to express their frustration at the Catholics' illegal activities.
They said police were despatched immediately to the site to ensure that violence did not erupt.
But the church claimed that the mobs attacked the believers and ransacked Thai Ha parish's property while the police looked on.
Meanwhile a stand-off continues at another disputed site in Nha Chung, central Hanoi. In a sudden move, the government began bulldozing the land last Friday for the construction of a park and a public library.
The Hanoi diocese wants the one-hectare plot, which once served as Vatican embassy and residence, to be returned.
But the government has refused, citing that historical claims of lands subject to "land management and socialist land reform policies in place before 1991" cannot be considered, according to Vietnamese law.
Mass prayers have been held since last December to protest against the policy.
The protests have put great pressure on the Hanoi government, which finds religious land disputes extremely difficult to deal with.
"If the government considered returning the lands to Thai Ha parish and the Hanoi Diocese, this would become an undesirable precedent for other Catholic organisations and individuals across the country. It would be extremely dangerous for the regime," Nguyen Van Trung, a lawyer who has been involved in a number of land cases, told the BBC Vietnamese Service.
The authorities have resorted to the safer solution of turning both disputed sites into public parks "to serve the people's interest".
But at the moment it does not seem to have satisfied the Catholic protesters, who claim that the lands are sacred to them.