"We will work so that such events never again happen," Kosor told reporters after her meeting with the European Commissioner for Justice, Viviane Reding, in Zagreb.
The Serbian prosecutorial authorities said on Thursday that they had withdrawn war crimes charges against Purda, Danko Maslov and Petar Janjic, due to a lack of evidence, after they had been accused of war crimes against the wounded and infirm in Vukovar.
Purda was arrested in Bosnia and Herzegovina on 5 January on a warrant issued by Serbia, and since then he has been in extradition custody in Zenica.