ADDIS ABABA, Ethiopia (AFP) — An oil tanker has been hijacked off the coast of Somalia and taken into its territorial waters, the British maritime security agency UKMTO said on Saturday.

The development added to risks for navigating in the Red Sea, which has become a more important supply route given the Iranian stranglehold on the Strait of Hormuz at the entrance to the Gulf, on the other side of the Arabian Peninsula.

The tanker was seized northeast of the Somali city of Mareeyo on Tuesday, UKMTO said.

“Military Authorities have reported unauthorized persons taking control of the tanker and maneuvering the vessel 77NM (nautical miles) south within Somali territorial waters,” it said.

Somali authorities did not immediately respond to Agence France-Presse queries about the hijacking.

Somalia is an unstable Horn of Africa country in which the central government contends with a fractured federation of semi-autonomous states, as well as frequent attacks by the Al-Qaeda-linked militant group Al-Shabaab.

It also opposes separatist status for Somaliland, a state whose claim of independence has been recognized only by Israel.

Somalia was the launching point for many pirate attacks in the past, with a peak in 2011. They have receded since, as the European Union, India and other powers have deployed navy missions to the area.

On the other side of the Gulf of Aden lies Yemen, where Houthi rebels armed by Iran have previously targeted shipping.

On Thursday, UKMTO said a Somali-flagged fishing vessel had been hijacked by 11 “armed individuals,” and a tanker was separately boarded by an armed group.