ATHENS, Greece (AP) — Greece and Italy signed an agreement Tuesday demarcating their maritime boundaries, amid tension in the Mediterranean region over rights to natural resources.

The agreement signed at the foreign ministry during a visit to Athens by Italian Foreign Minister Luigi Di Maio, tackled an issue that had been pending for 40 years, Greek Prime Minister Kyriakos Mitsotakis said in a statement.

“Today is a good day for Greece, Italy, Europe and the entire Mediterranean,” Mitsotakis said, adding that the deal meets international law and the United Nations Convention on the Law of the Sea.

It demarcates the exclusive economic zone — the maritime area in which a nation has the right of energy exploration and use of marine resources — between the two neighbors, as well as settling fishing rights, Greek Foreign Minister Nikos Dendias said after signing the deal with Di Maio. “Today is a historic day,” he said.

Greece and Cyprus in particular have been locked in a tense diplomatic standoff with Turkey over drilling rights at sea. The issue is complicated by the lack of clear agreements delineating countries’ exclusive economic zones.

Last November, Turkey signed a maritime boundary agreement with Libya’s UN-backed government that was strongly opposed and considered illegal by Greece, Egypt and Cyprus.

“The demarcation of maritime zones is achieved in accordance with international law, with valid agreements,” Dendias said. “Not with unsubstantiated agreements such as the agreement between Turkey and (Libyan Prime Minister Fayez) Sarraj.”

Dendias said he spoke with Di Maio about “the escalation of Turkish violations against our country,” noting in particular a demand by a Turkish oil company “to drill on the Greek continental shelf.”

NATO allies Greece and Turkey have long-standing disputes, including over territorial rights in the Aegean Sea.