On Tuesday Seks met the Vice-President of the Polish Parliament, Ludwik Dorn, President Lech Kaczynski and Foreign Minister Anna Fotyga.
The meetings focused on how Poland can help Croatia draw closer to the EU, on bilateral relations and on parliamentary cooperation.
The Croatian official was reassured that Croatia enjoyed Poland's support in its bid to become a full member of the EU before the settlement of the issue of a new European constitution.
Poland believes that the issue can be solved by amending the Treaty of Nice so that Croatia wouldn't be hostage to the crisis that emerged after the European Constitution was rejected at referendums in France and the Netherlands, Seks told reporters on Tuesday.
He added that Poland would oppose attempts to use contentious issues between Croatia on one side and Italy and Slovenia on the other to hamper Croatia's EU membership talks.