"None of us can exert pressure on the judicial institutions," said Kosor who together with the Bosnian Presidency members discussed the case of Croatian citizen Purda who was arrested on the Bosnian-Croatian border on an international warrant issued by Serbia, where he is wanted for alleged war crimes.
Purda has been in extradition custody in Zenica since his arrest on 5 January.
"However, I told them (the Presidency members) that the Croatian judicial institutions conducted interviews and the prosecutorial authorities established that Tihomir Purda is not guilty and that he is innocent," Kosor said expressing hope that Bosnian institutions would take this fact into account.
Kosor and the Presidency members -- Nebojsa Radmanovic, Bakir Izetbegovic and Zeljko Komsic -- who were on a two-day official visit to Zagreb, also discussed economic topics and agreed that 2010 had been a tough year.
Despite the crisis, trade between the two countries rose six percent last year, the Croatian premier said, adding that they had also considered possibilities for Croatian and Bosnian joint ventures on third markets.
The PM and the Bosnian guests also discussed an agreement on dual citizenship.
The current chairman of Bosnia's Presidency, Radmanovic, said that the agreement "has stuck" in Bosnia. However, responsibility for the lack of progress on demarcating the border lies with both countries equally, he said.
"We hope that Bosnia and Herzegovina will not have the kind of problems Croatia had (over the border) with one of European Union members," Radmanovic said.
Kosor said that upon its entry into the European Union, Croatia would continue supporting its first neighbours' Euro-Atlantic aspirations.
She reaffirmed Croatia's commitment to a single Bosnia and Herzegovina with the three constituent peoples and their equality, adding that Croatia's constitutional duty is to care about the Croats living outside Croatia.
The Bosnian Presidency members were received by Croatian President Ivo Josipovic on Monday afternoon and by Parliament Speaker Luka Bebic on Tuesday morning.