So far, the arrival of 16 presidents, three parliament speakers, 15 prime ministers, 10 deputy prime ministers and 11 foreign ministers has been confirmed. The number of foreign guests has risen to about 120, said Tomislav Saucha.
As for the European Union, it has been confirmed that European Council President Herman Van Rompuy, European Parliament President Martin Schulz and European Commission President Jose Manuel Barroso will come to the ceremony in Zagreb's main square.
As for EU members, Zagreb can expect the arrival of the presidents of Romania, Greece, Italy, Lithuania, Cyprus, the Czech Republic, and Slovenia, the chancellors of Austria and Germany as well as the prime ministers of Poland, Latvia, Hungary, Belgium, Slovakia and Malta.
With regard to Croatia's southeastern neighbours, they will be represented at the levels of head of state or government or foreign minister.
Saucha said that Presidents Tomislav Nikolic of Serbia and Atifete Jahjaga of Kosovo have confirmed their attendance.
Asked by reporters whether the Serbian president's arrival could be deemed definite in light of the fact that he made his attendance conditional on the non-invitaiton of Kosovo's top officials, Saucha said "a registration form for him (Nikolic) has been filled out. We regard it as an official confirmation and we are looking forward to all who will come."
The Pope's special envoy Giovanni Lajolo, U.S. Deputy Assistant Secretary of State Philip Reeker and Canadian Labour Minister Lisa Raitt are also expected at the ceremony.
The cost of the celebration, estimated at HRK 5.2 million (approx. 693,500 euros) in May, will be 10-15 per cent higher. Saucha said the budget was "fully aligned with the moment we are living in" and that the costs would be released after the event.
It is believed the foreign guests will start arriving in Zagreb after 11am on June 30. At 10am, a Croatian government delegation will lay wreaths in honour of killed defenders at Mirogoj cemetery.
The guests will start gathering at the government at 6.30pm. The delegation heads will be photographed together outside the government building at 8pm.
A programme for the public will begin at Zagreb's main square at 8.30pm, while the central celebration will begin at 11pm.
The main celebration will be addressed by Croatian PM Zoran Milanovic, Barroso, Irish Parliament Deputy Speaker Eamon Gilmore on behalf of the country wrapping up its presidency over the EU, Lithuanian President Dalia Grybauskaitce on behalf of the country assuming the six-month rotating presidency, Van Rompuy, Schulz, and Croatian President Ivo Josipovic.
The director of the central celebration, Dora Ruzdjak Podolski, said 681 performers would take part in the programme, which would be based on Croatia's protected cultural heritage, including those on UNESCO's list. She said Croatia was fourth by the number of items on the World Heritage List.
Ruzdjak Podolski said the programme would highlight Croatia's music, literature and science, adding that Nikola Tesla's transformer would be brought to Ban Jelacic Square as an example of outstanding Croatian creation to mark "an important moment just before EU entry."
The "Ode to Joy" will be performed at midnight.
There will also be video links with the Bajakovo and Bregana border crossings. The customs sign will be symbolically taken down at the Bregana crossing with Slovenia, while the EU sign will be placed at the Bajakovo crossing with Serbia, said Ruzdjak Podolski.
More than 500 reporters have been accredited for the central celebration in Zagreb.
Saucha announced another press conference about the event in a few days.
EU countries will also celebrate Croatia's accession. Croatian embassies in virtually every capital will organise concerts or exhibitions on the occasion of Croatian Statehood Day, June 25, and EU accession, July 1.