Libya's eastern parliament approved a maritime boundaries deal with Turkey on Tuesday, drawing swift condemnation from Greece which called it a violation of international law.
The deal is part of a years-old dispute over competing claims to sea borders and energy exploration rights in the eastern Mediterranean.
It was originally agreed in 2019 by Libya’s internationally recognised government in Tripoli in the west, but the rival eastern administration under military commander Khalifa Haftar had withheld its approval for years.
Greece, Egypt and Cyprus have long been opposed to the deal, which they see as infringing on their own maritime claims.
In a foreign ministry statement, Athens said the deal, "remains illegal, null and void, contravenes international law of the sea, and infringes upon the sovereign rights of states in the region."
"We call on the Libyan side to refrain from any action that contravenes international law and undermines stability in the Eastern Mediterranean," it said.
Turkey's foreign ministry welcomed the Libyan parliament's decision, saying the agreement respected the mutual rights and interests of both countries under international law and the principles of equity.
"Turkey will continue its determination to work together with all partners to ensure security, stability and peace in the Mediterranean basin," the ministry said.
Athens and Cairo signed an overlapping deal designating an exclusive economic zone in the eastern Mediterranean in 2020, which Turkey opposes.
Last year, Greece approved hydrocarbon exploration for a consortium led by US major Chevron south of Crete, condemned by Ankara as "unlawful."
Libya broke apart into rival eastern and western administrations more than a decade ago during a civil war after longtime Libyan leader Muammar Gaddafi was toppled by a NATO-backed uprising.
Turkish support was crucial to repelling an assault by Haftar's forces on Tripoli in 2019-2020.
But relations have steadily improved in recent years, with Turkish officials paying regular visits to Haftar’s de facto capital, Benghazi, and investing heavily in construction and other sectors.
In the same session, the eastern parliament also reversed a 2020 decision to cut off political ties with Ankara.
The move to ratify the deal marks a "complete reversal" which "reveals the depth of the relationship between Ankara and Benghazi today," said Anas El Gomati, head of the Sadeq Institute, a Libyan think tank.
The vote had been eased by the replacement earlier this month of the long-serving parliament speaker, Aguila Saleh, widely seen as an ally of Egypt, he added.
Saddam Haftar, the deputy of Haftar, welcomed parliament's approval in a statement, calling the deal "a tool that can help protect Libya’s rights and economic interests in the Mediterranean."
Libyan lawmaker Tarek al-Jeroushi told Reuters the agreement would strengthen Libya's position as a political, military and economic partner to major powers.
"Some countries may be upset by this agreement, but what matters to us is our national interest," he said.
Jalel Harchaoui, a contributor to Britain's Royal United Services Institute think tank, said the vote could also open the way to an expanded Turkish military presence in the east.
"Today's parliamentary ratification is a watershed," he said.
(Reporting by Ayman al-Warfalli in Benghazi, additional reporting by Ahmed Elumami in Tripoli, Alexander Dziadosz in Cairo, and Renee Maltezou in Athens; Writing by Tala Ramadan; Editing by Andrew Heavens, Alexandra Hudson)
