The level of demand is likely to determine whether the project on the island of Krk will go ahead.

"The first round for submitting binding bids ended on April 8. The second round will finish on May 6 and, in case a third round is necessary, it will close on May 23," the managing director of LNG Hrvatska, Goran Francic, told Reuters.

"The final results of demand for buying capacities in the terminal will be released on May 28."

LNG Hrvatska is preparing to build the floating terminal, which Croatia hopes will start operations in early 2020. The final investment decision is expected by the end of June.

The terminal, with projected capacity of 2.6 billion cubic metres of gas a year, is part of European Union efforts to diversify away from Russian energy imports, most notably for countries in central Europe.

The EU has said it would finance 28 percent of the terminal's value, or 101.4 million euros ($125 million).

The Jutarnji List daily reported over the weekend, citing sources familiar to the process, that demand reached only four percent of overall capacity in the first round of the tender.

"Given the confidentiality of the procedure we cannot comment on the first round results, but with a knowledge of how the gas traders operate we can expect their active involvement in the following rounds as the first round usually revolves around testing the market and competition," Francic said.