JERUSALEM (AP) — Israeli Prime Minister Benjamin Netanyahu made an unprecedented appearance at the Supreme Court Sunday to defend a deal signed in December with U.S. and Israeli developers drilling offshore gas deposits.

Israel's Channel 10 TV reported Netanyahu as telling the court that if Israel were to alter its deal investors could turn away and buy gas from Israel's enemies instead.

Netanyahu said he chose to speak in court because of the strategic importance of the gas deal, which he says will allow Israel to develop ties with Jordan, Egypt and Turkey and significantly boost its economy.

Resource-poor Israel announced the discovery of sizeable offshore natural gas deposits about five years ago. A partnership between Noble Energy and Delek Group, which is led by billionaire Yitzhak Tshuva, is the main developer at Israel's two larger gas fields, Tamar and the heftier Leviathan. After the country's antitrust commissioner determined the gas companies' ownership constituted a monopoly, a government committee reached a deal with the firms to introduce competition.

Opponents later challenged the deal in court because they said it favored the developers over the Israeli public.

Opposition lawmaker Shelly Yachimovich, a leading opponent of the deal, tweeted that Netanyahu's speech was full of "exaggerations, clichés and general statements without one fact behind them."

Israeli courts spokeswoman Shirley Koren said Netanyahu's appearance before the Supreme Court marked the first ever for a sitting prime minister.

Critics have accused Netanyahu of using high-handed tactics to bypass opponents of the deal. In January, Israel's economy minister resigned rather than overrule the antitrust commissioner who opposed the gas deal and later resigned in protest over it.

About 50 people protested outside the court Sunday. One wore a cape, a scepter and a mask of Netanyahu's face, while another held a sign that read "selling the state."