The Croatian Hydrocarbon Agency announced on Wednesday that a second licensing round will begin in September for exploration areas in both the Adriatic Sea and Slavonia.

The tender will be opened for seven months, during which time interested companies will receive documentation showing the potential for hydrocarbon exploitation and be asked to make a binding offer.

The companies that are granted licences will sign a two-year contract for exploration, followed by a three-year contract including exploitation as well. After a five-year period, the companies will be granted 25-year-long concessions for exploitation.

The Croatian government launched its first offshore tender in April 2014, which resulted in the granting of ten licences to three consortiums in January 2015.

After the first round, licenses for 19 exploration areas were not handed out and an additional seven became available on Monday, when a consortium consisting of Austria’s OMV and the US Marathon Oil Corporation decided to opt out of exploration for gas and oil in the Adriatic Sea.

The consortium decided not to sign a contract with the government partly because of a maritime border dispute between Croatia and Montenegro in the southern Adriatic, where three out of their seven exploration zones were located.

In the first round, a consortium consisting of Italy’s ENI and Medoilgas was granted one licence in the central Adriatic, while the Croatian-Hungarian INA received two licences in the south.

Although one of their two exploration areas lies in the disputed waters, INA has said it is still analysing these “new circumstances”.

The whole process has already fallen behind schedule, because the contract signing was first scheduled for April, then postponed to June due to concerns raised by Croatia’s maritime neighbours – Italy, Slovenia and Montenegro – and afterwards moved again to September.

Croatia launched its first onshore tender for Slavonia in July 2014, granting all six licences to three companies in June 2015. Canada’s Vermilion Zagreb Exploration received four, Nigeria’s OANDO PLC received one and INA received the final licence.

The Croatian government has said it expects that around 530 million euro will be invested by the companies involved.