The police have launched a criminal investigation in a high profile land dispute that exploded into violence in April, despite a pledge at the time that no-one would be prosecuted.
The move has sparked allegations of deception and risks inflaming tensions over the confrontation in Dong Tam commune near Hanoi, where villagers rose up in open defiance of the Communist party authorities.
Residents took 38 police and officials hostage in mid-April after the police arrested a number of land rights campaigners. The locals released their final captives a week later after the Mayor of Hanoi, Nguyen Duc Chung, gave assurances of immunity for those involved.
Police announced on Monday that they would open a criminal investigation into the illegal detention of officials and what they called vandalism carried out in the village during the confrontation.
Social media immediately lit up with allegations that the authorities had broken their promise and shown that their word could not be trusted.
Government taken by surprise
The peaceful resolution of the standoff at Dong Tam came as a surprise to many who expected severe retribution from the authorities.
For a week, villagers had kept police at bay by building barricades around their village and threatening to harm the officials they were holding captive.
The ferocity of the uprising appeared to take the government by surprise.
The conflict underlined the extreme volatility of many land disputes across the country where local people believe they have been cheated by developers in league with Communist party officials.
In Dong Tam, a rural commune about 35 km south-west of Hanoi, the military owned telecom company, Viettel, has plans to build an airport on disputed land.
The mayor of Hanoi had personally intervened in the negotiations and secured a peaceful settlement and the release of the remaining hostages.
He promised a through investigation into the causes of the dispute and signed a letter saying that the villagers would not be prosecuted for their actions.
The decision by the police to investigate, two months after the event, will confirm the suspicion of many that they were never sincere about the pledge.
Observers point out that the Communist party is not known for conciliatory responses to those that openly defy its authority.