Updated

Bulgarian prosecutors have pressed charges against four former police officials accused of involvement in wiretapping political opponents of the former government.

The prosecutor's office charged on Tuesday the most recent head of a police surveillance unit, Sergey Katsarov, and his two predecessors Tsvetan Ivanov and Kamen Kostov with abuse of power and facilitating unregulated wiretapping between 2009 and 2013. A fourth official, Radko Dimitrov, was charged with attempts to cover up the case by allegedly destroying the illegal recordings.

The accused deny the charges.

The prosecution opened a probe last month and found evidence of possible unregulated wiretapping of politicians, businessmen and magistrates.

Bulgarian legislation allows technical means of surveillance to be used only in investigations into a crime that carries a prison sentence of more than five years.