The head of the financial security department at Bulgaria's counter-intelligence agency DANS is to be put trial over the alleged disclosure of a state secret, the prosecution says.

According to the anti-corruption unit with the Sofia City Prosecutor's Office, the Miroslav M. allegedly made public information from 11 classified documents that were tantamount to a state secret.

The alleged wrongdoing happened between September 2013 and October 2015, and the disclosure carried "particularly grave consequences for state security", prosecutors believe.

M. handed over the documents to a former collaborator to DANS and the National Investigative Office for financial purposes.

The volunteering collaborator had been helping the two agencies since 2006, but had been never granted access to classified information.

M. allegedly handed copies of the documents relating to certain companies, demanding that the collaborator make company representatives familiar with their content and ask them to cooperate with financial assistance to make sure they will not have "problems with DANS".

"The information contained in the documents reveals data about events and actions against the economic and financial security of the state, reveals the operational interest in the people concerned, the information already gathered about them and other people having committed or preparing to commit crimes endangering national security," the prosecution says.

DANS, Bulgaria's domestic security and counter-intelligence agency, was set up in 2008, and ever since has come under the spotlight several times in relation to activities of its current or former officials.