BELGRADE, (Reuters) – Four ministers of the liberal G17 Plus party in Serbia’s ruling minority coalition will submit letters of resignation to Prime Minister Vojislav Kostunica today, a senior party source told Reuters. If accepted, their move would bring down the two-and-a-half year-old government, triggering a snap general election that media reports speculate could be held in December. The liberals’ decision, which they warned of four months ago, is linked to a freeze imposed on talks with Serbia by the European Union because it has failed to arrest war crimes fugitive Ratko Mladic, the Bosnian-Serb wartime commander. The liberals hold the finance, health and agriculture portfolios in Kostunica’s Cabinet and Ivana Dulic-Markovic of G17 Plus is also deputy prime minister. G17 Plus leader Miroljub Labus resigned as deputy prime minister in May, saying Kostunica’s reluctance to track down and arrest Mladic was harming Serbia’s efforts to join the European Union, a lengthy process which Brussels has tightly linked to Belgrade’s respect for international law. The party warned Kostunica at the time that it would walk out on the government and withdraw the support of its 31 deputies in Parliament if the EU talks had not been resumed by October 1. That looks unlikely. UN war crimes tribunal chief prosecutor Carla del Ponte was due to meet with EU Enlargement Commissioner Olli Rehn at an event in Finland today and, as far as is known, there is little progress to report. Del Ponte is due to visit Serbia at the start of next week.