The head of the Humanitarian Law Fund, Natasa Kandic, told Radio B92 that Tadic's statement, given in a Croatian Television talk show on Sunday, was the most serious apology to be heard so far in the region.
"Assuming responsibility gives the most serious tone to his apology. After that statement, one can expect cooperation with the Hague war crimes tribunal to be completed and all obligations towards the tribunal to be met and all indictees to be handed over," Kandic said.
The head of the Serbian Helsinki Committee for Human Rights, Sonja Biserko, told Beta news agency that Tadic's apology was "welcome" and that it would serve to improve relations between the two countries.
Liberal-Democratic Party leader Cedomir Jovanovic said he had nothing against the Serbian president apologising to Croatian citizens, but that "words alone are not enough".
"Relations between Serbia and Croatia were disrupted by a policy that was the result of a wrong value system and that continues to exist in Serbia," Jovanovic told Beta news agency, adding that the wrong policy was surviving thanks to the coalition between Tadic and Prime Minister Vojislav Kostunica, whose party has not commented on Tadic's gesture yet.
An official of the G17 Plus party, Snezana Stojanovic, said Tadic's apology was "a good gesture of a statesman" and added that the Serbian society had to come to terms with its past and admit, individualise and condemn the crimes that were committed.
Serbian Radical Party secretary-general Aleksandar Vucic called Tadic "the biggest disaster and a disgrace for Serbia, because he apologised to the Croats for the killing and expulsion of Serbs."
"He directly accused Serbia of causing the war in the former Yugoslavia. He apologised to the Croats for all that they had done, from the time of Ante Pavelic to the time of Franjo Tudjman. For their killing hundreds of thousands of Serbs and for expelling millions more from their homes," Vucic told Beta.
A member of the Socialist Party of Serbia, Zarko Obradovic, expressed disappointment at Tadic's statement, adding that Tadic was admitting "something that objectively does not exist".
Aleksandar Popov, coordinator of the Igman Initiative which gathers 140 NGOs from the region, told Beta that Tadic's apology seemed sincere and he welcomed it, hoping that it would facilitate efforts to normalise relations between the two countries.
The head of Belgrade's Human Rights Centre, Vojin Dimitrijevic, said that Tadic's statement "is a great move of a Serbian statesman, because relations between Croatia and Serbia must be normalised".