The talks between the two officials marked the start of a Croatian parliamentary delegation's two-day visit to Baden-Wuerttemberg.
Straub said Croatia's relations with both Germany and Baden-Wuerttemberg were excellent, adding that 140,000 of the 400,000 Croats living in Germany reside in Baden-Wuerttemberg. He voiced satisfaction that Croatia's biggest consular office was in Stuttgart.
Straub recalled Baden-Wuerttemberg Prime Minister Erwin Teufel's visit to Croatia last October, when a cooperation agreement was signed and it was agreed to set up a mixed commission between Croatia and the German state, which held its constituent session in Zagreb in March.
Seks said the commission's work would improve cooperation, including between parliaments.
He suggested parliamentary committees should exchange visits focusing on issues of common interests, such as the economy and tourism, which Straub accepted, saying that such cooperation could begin only next March after parliamentary elections in Germany.
Seks said his visit would focus on the strengthening of economic relations, given that Germany is the second largest investor in Croatia and that Baden-Wuerttemberg accounts for more than 15 per cent of those investments.
Regarding the process of Croatia's admission to the European Union, Seks said the postponement of entry talks in March was a big disappointment for Croatia given that prior to that it had been assessed as a functioning market democracy. He added that further delays might increase the number of Eurosceptics, given that currently public support for joining the Union revolves around 50 per cent.
Straub, who also chairs the EU Committee of the Regions, said the committee supported Croatia's admission to the Union as soon as possible.
He announced that at a plenary session in July, the committee would adopt draft principles, priorities and terms of partnership with Croatia, which will then be put to the Council of Ministers.
Straub said that although the committee's role is only advisory, the draft would be very positive for Croatia. He hoped the Council of Minister would consider it.
Two weeks ago Straub held talks with Austria's most senior officials, including President Heinz Fischer and Chancellor Wolfgang Schuessel. He told Seks that they all supported Croatia's efforts to join the EU.
Straub said the Austrian officials concluded it was unacceptable for an entire people to be held collectively responsible for one individual, alluding to the runaway general Ante Gotovina, who is wanted by the Hague war crimes tribunal and whose non-extradition was the reason why the entry talks were postponed in March.
Straub told the Croatian delegation the situation in the EU was very difficult following the rejection of the European Constitution in France and the Netherlands, and that it was difficult to estimate how it would develop. He said that in Great Britain, which will chair the Union in the second half of the year, the opposition to the Constitution was also strong. He added it could be heard that the issue of further enlargement might be linked to Turkey.