The leader of the Alliance of Independent Social Democrats (SNSD), Milorad Dodik, said in the northwestern city of Banja Luka on Tuesday that the agreement was also made on the continuation of the entity model of voting in the House of Representatives in the Bosnian parliament.
Mladen Ivanic of the Party of Democratic Progress (PDP) added that the three major parties from the Serb entity ensured changes at the state level, "preserving at the same time the fundamental values of the entities".
The 1995 Dayton peace accords, whose amending is the central topic of the negotiations of the main eight parties in Bosnia, divided the country into the two entities: the Republic of Srpska and the Muslim-Croat Federation of Bosnia-Herzegovina.
Officials of the parties from the Muslim-Croat entity have not yet confirmed that any progress was achieved at the Sarajevo meeting.
The leader of the Muslim-dominated Party of Democratic Action (SDA), Sulejman Tihic, has only said that a final phase of the negotiations can be expected this week with the adoption of over 70 amendments to the Bosnian Constitution.
However, the Party for Bosnia-Herzegovina (SBiH) and the Croatian Democratic Party in Bosnia (HDZ BiH) oppose the adoption of the changes discussed by the Bosnian Serbs.
SBiH officials believe that the proposed changes would only cement the current division between the two entities.
HDZ officials ruled out any agreement that would not include the opening of discussions on the reorganisation of the medium-level authorities with the prospects of abolishing the entities.
The negotiations on the Bosnian constitutional changes have been going on for nine months with the eight major parties taking part in them.
Two days ago, five parties attended the talks which resumed at the U.S. Ambassador Douglas McElehaney's initiative after they were discontinued in January.
A final agreement should be reached by March, which would leave enough time to elaborate the deal into laws in order to create conditions for holding the next parliamentary elections in autumn in line with the new rules.