The Israeli government has agreed to changes in the agreement, under which the U.S.-Israeli developers of its huge offshore natural gas fields operate, that is expected to propel the largest-ever infrastructure project in the country’s history.

The revised agreement was approved after Israel’s supreme court in late March ruled as unconstitutional a clause in the initial pact that had guaranteed no alterations in its terms over the next 10 years, even with changes in the country's government. The ruling had halted plans by developers Houston-based Noble Energy Inc. and its Israeli partner, Delek Group to spend up to $10 billion in gas sector infrastructure, with some observers then anticipating a long delay in investment commitment.

Noble Energy and Delek Group believe they will be able to begin production at the Leviathan offshore gas field by the end of 2019, although many experts say it will take at least another year.

Israeli financial-industry sources said that, after a freeze imposed over a year ago, Delek Group and Noble Energy have resumed contacts with lenders to fund the project. On May 22, Delek Group subsidiaries Delek Drilling and Avner Oil and Gas announced that the developers are expected to make a final decision by the end of the year on the massive investment in the offshore field.

“This will be the largest infrastructure investment ever undertaken in Israel and could top $10 billion,” said Chen Herzog, chief economist and energy expert at BDO Consulting. By comparison, total infrastructure investment in Israel last year was approximately $7 billion. Earlier this year, Delek Group estimated the initial development cost at $5 billion to $6 billion—down by more than 20% from a previous estimate—due to a drop in the cost of rigs and other equipment as oil and gas prices have sharply declined.

The figure includes the development of eight production wells, a production-and-treatment platform, and undersea pipelines, which will run to Israel's coast to serve the domestic market, as well as Jordan and Palestine. In recent weeks, two supply agreements worth a total of about $4.3 billion have been signed with two Israeli private power plants for gas from the other offshore gas field, Tamar. Already in the advanced planning stages, a 20-kilometer-long pipeline will link Israel’s and Jordan's transmission networks.

The largest export potential is to Egypt and Turkey, but that would entail billions of dollars in marine pipelines. The only route large enough for Israeli exports would be through Turkey, according to Shai Cohen, Israel’s consul general in Istanbul. Such a plan would requirel an investment of around $4 billion in pipelines and other infrastructure, he noted. Israeli and Turkish companies have been discussing the project, which would serve the Turkish market and link the existing gas-pipeline network to Europe.

Israeli diplomatic sources said a green light for a gas deal with Turkey could come in the next few weeks, once the two countries have resolved the political tensions that arose in 2010, when Israel made a naval commando raid against a Turkish ship that was trying to evade the Israeli blockade on the Palestine-controlled Gaza Strip.