Kolaric said she unofficially heard that the party initiated her ousting, adding that she was shocked and that she was "guilty of publicly stating my position, which is different from the position of party president Zoran Milanovic."
Kolaric criticised Milanovic in a column on the Index.hr web portal on Tuesday over Croatia's law on the European Arrest Warrant, saying the prime minister had "caused a pointless quarrel with the European Commission, leading to Croatia facing possible sanctions."
Via Facebook, she said the procedure to oust her indicated "the key problem of our party: silence, fear and autocracy of the party president."
She also said her ousting "was especially requested by (Labour) Minister Mirando Mrsic and (Enterprise) Minister Gordan Maras, and the president of the party supported him. Only Davor Bernardic voted against it."
Kolaric is president of the Croatian Public Relations Association and a candidate for vice president of the SDP's Zagreb branch. At the time of the Ivica Racan Cabinet a decade ago, she was the government's spokesperson and chief of staff of its public relations office.
Mrsic, a member of the party presidency, issued a statement refuting Kolaric's claims in the media that he had demanded the presidency discuss an open letter by her and initiated her ousting from the party.
Mrsic said he advocated open dialogue, party unity and the acknowledgement of everyone's opinion, but that he was "against calls to overthrow a democratically elected leadership."