Partners behind one of the largest natural gas fields in the Mediterranean Sea said they're planning more drilling with the aim of starting production in 2019.

Delek Group and its partners at the Leviathan natural gas field off the coast of Israel announced plans for appraisal and production operations in the region. Delek Group President and CEO Asaf Bartfeld said the appraisal is part of a series of steps aimed at uncorking the field's full potential.

"These steps, as well as authorizing the Delek Group partnerships to take the final investment decision for development of the field, will allow us to comply with the timetables to produce natural gas from Leviathan by the end of 2019," he said in a statement.

Delek this year was forced to defend its development plans for Leviathan after a report from the Israeli government said that, after a review from independent analysts, the field could support production of about 20 percent less than Delek and its partners had estimated.

The Leviathan partnership approved a development plan last week that calls for production of around 1.2 billion cubic feet of natural gas per day through an investment of between $3.5 billion and $4 billion.

A good portion of the gas reserves in Leviathan are designated for exports. Early this month, the Leviathan partners reached an agreement with Dalia, the largest private power plant in Israel, to supply fuel for up to 20 years once production at the field begins, however.

In their opinion, the partners said cumulative revenue for the sales agreement "is likely to come to $2 billion," assuming Dalia takes on the full amount of gas outlined in the terms of the deal.