Volen Siderov, leader of Bulgarian nationalist party Ataka, has accused President Rosen Plevneliev of issuing an unconstitutional decree for the appointment of a caretaker government.

Speaking at a press conference on Monday, Siderov told journalists that Ataka had notified Bulgarian Ombudsman Konstantin Penchev about the matter and expected him to address the Constitutional Court (KS).

The nationalist leader, as cited by Darik radio, argued that the decree for the appointment of a caretaker government was unconstitutional because it introduced structural changes which were the prerogative of Parliament.

"Rosen Plevneliev violated the Constitution. There is no law which entitles him to make structural changes. He created a Ministry for Electronic Government and established posts of three Deputy Prime Ministers and this runs against the Constitution. He also violated the E-Government Act," Siderov stated, as cited by LiveNews.

The nationalist leader suggested that the presidential decree could not be partially revoked in its section concerning the new E-government Minister but had to be cancelled in its entirety, alongside the decree for the dissolution of Parliament.

Siderov claimed that Plevneliev's misstep was reason enough to seek an impeachment procedure after the early elections.

Bulgaria's center-right GERB government resigned on February 20 amid mass protests over high heating and electricity bills and low incomes.

The panel of the caretaker government was announced by President Plevneliev on March 12 and the early elections were scheduled for May 12.