Investigators questioned Sungurlare mayor Dimitar Gavazov for four hours, but he stays in custody. A court hearing on his detention is due tomorrow, and a protest is expected outside.

The organised crime unit (GDBOP) and the State Agency for National Security (DANS) began their operation in the municipality on Tuesday, 20 October. Early reports pointed to rigged public procurement. Investigators seized documents from the town administration. They are checking whether work was falsely recorded as done, whether contractors were picked in breach of the rules, and whether the sums paid match the work actually carried out.

The previous development: GDBOP and DANS detain people during a joint operation in Sungurlare and Burgas

Two municipal employees were held briefly and have been released. One is an auditor in the administration, the other an expert in public procurement. Unofficial reports say both gave evidence against the mayor. Other municipal staff who were questioned were also let go.

Hristo Shirokov, the regional leader of the DPS party, was also questioned. He is under house arrest in another case.

Deputy mayor Tatyana Ivanova said she is worried only about Gavazov and cannot say what exactly is being investigated. She said there may be four public procurement cases, but she is not sure.

The mayor's sister says no one should be tried or detained over their choice, and that the right to choose comes above everything. The party does not come first, she said. Asked whether her brother was detained because of the party, she said that was most likely the case.

Prosecutors are also investigating Belitsa mayor Radoslav Revanski, a deputy chair of the DPS. He was detained for 72 hours after an operation that began yesterday. Police searched the town hall and his home. Early reports say the checks concern public procurement, projects of the Road Infrastructure Agency and EU funding.

Tension rose as Revanski was led out in front of the town hall in Belitsa, and crowds chanted in his support. DPS leader Delyan Peevski came to the scene and accused the ruling parties of political repression. Revanski also criticised the authorities' actions.

Detention and investigation do not in themselves prove the guilt of either mayor.

Investigators are also expected to question a representative of another municipality who is linked to the DPS headquarters.