BENGHAZI, Libya/TUNIS (Reuters) - Residents of Derna in east Libya say they are facing critical shortages after Khalifa Haftar’s Libyan National Army (LNA) tightened its longstanding siege around the city last week.

Haftar’s eastern-based LNA, one of a number of factions that have vied for power in Libya since a 2011 uprising ended Muammar Gaddafi’s four-decade rule, is waging a military campaign against a coalition of Islamist militants and ex-rebels known as the Derna Mujahideen Shura Council (DMSC) that controls Derna.

Attention has shifted to the coastal city after Haftar announced victory in a three-year military campaign against a similar coalition in Benghazi, 350 km (210 miles) to the west, a month ago.

The LNA launches occasional air strikes over Derna and at the end of July, one of its fighter jets was shot down. The pilot was killed. The LNA subsequently reinforced its siege.

“The situation is extremely bad. Everything is stopped, the supplies are depleted and nothing is getting into the city,” one resident told Reuters by telephone.

“There is a total blockade with no entry or exit. They only allow you to leave as a displaced person.”

Another resident said most bakeries had closed because of a shortage of fuel, and that petrol stations had been shut for eight months. There was an acute shortage of medicine, he said, though some oxygen tanks were delivered to a hospital in Derna on Monday.

The United Nations humanitarian coordinator for Libya has expressed concern over reports of “severe shortages of basic necessities, including life saving medical supplies” in Derna, while the U.N.-backed Government of National Accord (GNA) in Tripoli called on all sides to “facilitate ways to provide for all the needs of the citizens”.

The LNA is aligned with a parliament and government based in the eastern Libya that has spurned the GNA.

Haftar and the head of the GNA met in Paris in late July amid efforts to broker a peace settlement for Libya. A ceasefire was announced, though it excluded “counter-terrorism” operations. The LNA commonly brands its rivals as terrorists.

Derna has a history of militancy. It was occupied by Islamic State militants in late 2014, but they were later ousted by the DMSC. Since then, forces loyal to the LNA have bolstered their blockade. Supplies of food, cash and medicine were disrupted or confiscated even before the latest tightening of the siege.

The LNA says it has been hitting militant targets that it has identified on the outskirts of in Derna, including ammunition stores. It says it is preparing to use further strikes if peace efforts with local leaders fail.

In May, the city was also a target of Egyptian air strikes. Egypt said it was responding to an attack against Coptic Christians on its territory, though that attack was claimed by Islamic State.

Haftar, a figure many believe is seeking national power in Libya, has enjoyed strong backing from Egyptian President Abdel Fattah al-Sisi, as well as the United Arab Emirates.

Western envoys have met Haftar frequently in recent months, and say he has to be part of any solution to Libya’s conflict.