Right-wing Reformist Bloc (RB) coalition will only make offers on a next cabinet in case the President gives them a mandate to form it, RB officials have said.

A meeting between the RB and Bulgaria's biggest party GERB, with its leader and outgoing Prime Minister Boyko Borisov also present, has kicked off political consultations with parties in Parliament that precede a presidential move to hand the mandate to a third party "of his choice".

The head of state, Rosen Plevneliev, last week indicated he only stood ready to give out the mandate to the RB, after handing it over to the Bulgarian Socialist Party (BSP), which insist it will return it upon receiving it.

Bulgaria plunged into political uncertainty in mid-November after Borisov stepped down. Last week he also refused to try to form another government.

News website Dnevnik.bg quotes the RB's Executive Council, the bloc's desicionmaking body, as saying consultations will only be carried out with parties sharing a "Euro-Atlanticist orientation" and "democratic values."

The RB said it decision means the BSP and the third-largest party, the Movement of Rights and Freedoms (DPS) which is dominated by ethnic Turks, will be left out of any talks.

While the RB is determined to take part in a new majority if enabled to form one through a mandate, it will not appoint political figures as ministers.

GEBR officials sent out positive signals after meeting the RB's leadership, with key lawmaker and Parliament finance committee head Menda Stoyanova praising the bloc for not being "like the Patriotic Front", which began drafting a cabinet without a mandate.

Stoyanova, however, made it clear official government negotations could not be held with the RB before it was assigned to seek a new cabinet.

The RB is a loose alliance of centrist to right-wing parties that was the junior coalition partner in the outgoing government. One of its parties, DSB, moved into opposition last December but remained within the RB's parliamentary group and kept its minister in the government.

The Patriotic Front, a nationalist coalition that backed the cabinet to secure for it a parliamentary majority but had no ministers, says it will try to form a new government if it receives a mandate.