Qatar on Sunday announced it had entered a consortium to explore Lebanese offshore gas in waters bordering Israel, following a historic border deal last year between the two foes.

The agreement greenlights Lebanon's exploration of its southern Qana, or Sidon, reservoir following the signing of the landmark deal last October demarcating its maritime borders with long-time enemy Israel.

Sunday's deal will see the gas-rich Gulf country's state-run QatarEnergy receive a minority 30 percent stake in two blocks of Lebanon's exclusive economic zone, according to Lebanese caretaker Prime Minister Najib Mikati.

French company TotalEnergies and Italy's Eni will both retain 35 percent shares in the blocks after Russia's Novatek relinquished its minority stake in 2022.

Lebanese Energy Minister Walid Fayad and his Qatari counterpart Saad al-Kaabi, who is also QatarEnergy's chief executive, signed the deal Sunday, along with the Eni and TotalEnergies chiefs.

Under a United States-brokered accord, Lebanon and Israel, which are officially still at war, delimited their maritime borders in October 2022.

The accord paved the way for Lebanon to begin exploration in the Qana reservoir -- which is partly located inside Israel's territorial waters -- in return for compensation payments.

According to energy consultant Naji Abi Aad, "Qatar's entry into the consortium is above all politically significant."

He told AFP that Doha's involvement "brings a political guarantee" as Lebanon grapples with deep economic, political and social crises.

Lebanon has been caught in an economic quagmire that has plunged much of its population into poverty and is described by the World Bank as one of the worst in modern history.