The statement of the Force of Serbia Movement, carried by the news agencies Tanjug and Fonet, said that Mesic and Karic agreed that lasting peace and stability in the region could be established only if all countries in the region established ties and joined Euro-Atlantic integration processes as soon as possible.
Asked for a comment, the source at President Mesic's office said that the meeting did take place, but added that it was very brief and accidental and that it was held outside the presidential offices.
According to the statement issued by the Force of Serbia Movement, "after meetings with officials from Croatia and Bosnia-Herzegovina", Karic will continue visits and talks with officials from other countries in the region, representatives of European institutions in Brussels and officials of Austria, the current EU chair.
After he showed up briefly in Belgrade on Tuesday to attend a rally organised by his party, at which he sought early parliamentary elections, Karic again left the country.
At the end of last year the Serbian government revoked the operating licence of the "Mobtel" mobile phone operator, until recently owned by Karic. After an investigation into the company's operations, charges were pressed against several company employees as well as Karic's brother and his wife on suspicion of embezzling 2.8 million euros in taxes.
Karic has accused Serbian Prime Minister Vojislav Kostunica and the government of conducting a campaign of political persecution against him.