Bulgarian National Bank (BNB)'s Deputy Governor Tsvetan Gounev has been accused of administrative abuse since Tuesday, investigation officials say.

The BNB has confirmed that pre-trial proceedings have been launched against Gounev, who also heads the Banking Supervision Department.

Bank representatives are quoted by the Bulgarian National Radio as saying that has taken leave until the end of judicial proceedings.

Authorities have provided no specific information, but have reportedly cited failure to exert oversight on banks granting "bad loans" according to Dariknews.bg.

In a letter to the public broadcaster, however, an employee of the bank who wished to remain anonymous said that Gounev's department did not apply "indiscriminately" legal requirements to all commercial banks in Bulgarira.

The employee described BNB Governor Ivan Iskrov and Deputy Governor Gounev as the ones being responsible for this malpractice and also as "financially dependent" on a "certain bank that has become notorious over the last days".

Gounev assumed office in June 2013 after the term of his predecessor, Rumen Simeonov, expired.