"Flanders ranks third in Europe in terms of Gross National Income per capita and I believe that their interests and our will to cooperate will produce positive results," the Croatian president said.
Leterme said that the Flemish government had set up a fund for EU membership candidates, and that the fund was very important because it promoted good relations among nations.
This year the Flemish government will earmark 500,000 euros from that fund for projects in Croatia.
That money can be used for various projects ranging from agriculture to research and labour, Leterme explained.
He congratulated Croatia on starting accession talks with the European union, expressing hope that it would join the bloc as soon as possible.
Flanders is Belgium's most developed region. Its exports account for 80 per cent of Belgian exports, and the Flemish government independently concludes agreements in various areas, including tourism and foreign trade.
Mesic arrived in Belgium on Thursday for a two-day visit. In the afternoon, he is scheduled to visit the port of Antwerp, and in the evening he will deliver a talk on the aspirations of Southeast European countries to join the EU.