Bulgaria's Parliament is to convene on Tuesday, with a proposal to hold a referendum on voting rules set a single issue on the agenda.

Lawmakers were initially poised to discuss on Thursday a referendum petition allowing citizens to have their say on majority elections system, mandatory voting, and e-voting, but lack of quorum hindered the session.

Both President Plevneliev and and an Initiative Committee have demanded that a poll take place, with the latter having submitted a 500 000-strong petition to Parliament in spring.

Ruling Bulgarian Socialist Party (BSP) MPs have long resisted the idea of a referendum, but a statement by leader Sergey Stanishev in which he stood for the introduction of mandatory voting has market a shift in the attitude of some party members, even though others still reject the proposal.

The plenary meeting, which has been called by Parliament Speaker Mihail Mikov and which could give green light to a poll amending electoral legislation, is due to coincide with the Consultative Council for National Security scheduled for Tuesday upon request by President Rosen Plevneliev.

A suitable date for early elections and a Bulgarian EU Commissioner nomination which could be put forward for the new European executive body, as well as ways to restore frozen EU funding will be among the main issues discussed at the Council.