Libya’s Defense Ministry threatened to sink a Maltese tanker its navy said it had fired upon on Sunday if it tried to dock in Sidra, a port city that is controlled by eastern federalists.

“If a ship docks in one of the closed ports and it does not leave the port again, then we will destroy it,” warned a ministry spokesman.

Demands

Armed protesters demanding more autonomy for Cyrenaica, the eastern part of Libya, have seized the port facilities at Sidra and threatened to ship oil independently. On Tuesday, they said they would guarantee security for vessels docking at ports under their control.

The rebels also control the export facilities at Ra’s Lanuf and Zuwetina. The three ports accounted for 600,000 barrels in crude oil exports per day before the start of the Libyan revolt that toppled longtime dictator Muammar Gaddafi in 2011.

Unrest throughout Libya last year cut its oil output to 250,000 barrels per day from 1.4 million.

Divisions

The central government in Tripoli has struggled to provide security throughout the country since Gaddafi’s regime collapsed. Autonomy movements have emerged in Fezzan in the southwest as well as the northeast, the region that is home to Libya’s minority Berber population.

The movement in Cyrenaica poses the biggest challenge. The region was only joined with the west, also known as Tripolitania, by the Italians when they revived the classical name “Libya” to describe their North African colony in the 1930s. After independence, Benghazi became the home of the Libyan monarchy. Before Gaddafi took over in 1969, the country was run along federal lines with Cyrenaica, Fezzan and Tripolitania each enjoying a high degree of autonomy. Gaddafi, a westerner, neglected the east in favor of economic development around the new capital, Tripoli.

The transitional government in Tripoli has so far rejected Cyrenaica’s federalist pretensions, fearing they might lead to the disintegration of the Libyan state. Talks have not borne fruit.

Berbers

Negotiations did lead the reopening of the El Sharara oilfield in the south of Libya, where production rose to over two-thirds of capacity on Tuesday. A pipeline feeding the port of Mellitah west of Tripoli has also been reopened.

The port itself was shut in November when a Berber militia seized it in order to pressure the central government into recognizing their culture and language.