Before the summit, Sanader will participate in a panel discussion organised by the Hanns Seidel Foundation.
The moderators of the discussion, focusing on Croatia's European Union accession negotiations, will be journalists of the newspapers Die Welt and the Financial Times Deutschland.
According to unofficial sources, there is a possibility for a meeting between Sanader and his Slovenian counterpart Borut Pahor, who will also attend the EU summit in Brussels.
On Thursday morning, European Union Enlargement Commissioner Olli Rehn and the Croatian and Slovenian foreign ministers, Gordan Jandrokovic and Samuel Zbogar, will hold a new meeting on the two countries' border dispute and the current standstill in Croatia's EU accession negotiations caused by that row.