An ownership squabble over Cyprus’ main natural gas field is threatening to delay multi-billion dollar plans to turn the eastern Mediterranean into a major energy hub.

Israeli Prime Minister Benjamin Netanyahu and Energy Minister Yuval Steinitz are flying to Cyprus on May 8 to spur plans to join the two countries’ electricity grids and construct a pipeline to link newly found gas fields to mainland Europe.

Standing in the way, however, is a dispute over Aphrodite, a gas field discovered in 2011 at the edge of Cyprus’ economic waters. One tip of it stretches across the border into Israel’s maritime zone.

Also, Egyptian Petroleum Minister Tarek El Molla said on May 7 that a planned pipeline connecting Cyprus’ Aphrodite gas field to Egypt’s LNG facilities will cost between $800 million and $1 billion.

Egypt has rapidly increased its production of natural gas and hopes to become a hub for exporting to Europe after making a series of big discoveries in recent years.

Egypt hopes to halt gas imports by 2019 and achieve self-sufficiency. Egypt has an extensive pipeline network and two idle gas liquefaction plants ready to export new gas as it arrives.

At stake in the gas field dispute is 7 billion cubic meters (Bcm) 10 Bcm of gas worth close to $1.5 billion, according to one recent estimate in Israel.

That is less than 10% of Aphrodite’s total reserves and a fraction of the gas already discovered in Israel.

Israel says it will not give up on the gas and the companies operating on the Israeli side are ready for legal action in case Aphrodite is developed without them.

“I assume we will find a solution in good spirit so we can keep cooperating on bigger, more important, things,” Steinitz told Reuters.

Several large gas fields have been discovered in the region over the past decade and Israel and Cyprus have grown close while collaborating in their development.

Steinitz says he and his Cypriot counterpart, Yiorgos Lakkotrypis, have become good friends.

But that does not guarantee a quick solution.

“The government of Israel cannot give up, not even as a gesture of friendship, on its territories or its natural resources,” Steinitz said.

He said the governments have asked the companies to reach an understanding among themselves on how much gas is on each side.

“If they don’t reach an understanding, then we will ask a professional arbiter or a professional group ... to examine the findings from both sides and decide on the proper division,” he said.

Charles Ellinas, CEO of energy consultancy e-CNHC, said this should not be a deal breaker.

“If the two governments between them agree to abide by the findings of the arbitration then it takes the heat out of it. And that’s what they need to do at this meeting this week,” he said.