Serbian President Boris Tadic accused today Croatian President Stjepan Mesic of warmongering, two days after Mesic said that he would intervene militarily if Bosnia's Serbian entity made a move to secede, according to dpa. Mesic's statement is a security threat and a war incitement, Tadic told Beta news agency, adding that he would inform the UN Security Council about it. Mesic on Monday commented on recent threats by Bosnian Serb leader Milorad Dodik to hold a referendum on the secession from Bosnia of the Serb Republic - one of two Bosnia's entities. The other is Muslim-Croat Federation of Bosnia-Herzegovina. Ties between Serbia and Croatia have been strained ever since the 1990s break-up of the former Yugoslavia. Zagreb sued Belgrade in 1991 before the International Court of Justice and Belgrade responded with a counter suit last month. Mesic strained the ties even worse earlier this month after he reduced a sentence for a convicted war criminal and then visited Kosovo, a separatist region Serbia claims as its own. Analysts say Mesic appears to be stepping up the pressure in making matters difficult for Serbia's new president-elect Ivo Josipovic who will take power on February 18.