ADDIS ABABA, July 7 (Reuters) - Ethiopia said on Wednesday that it had allowed humanitarian flights to its northern Tigray region this week, amid concerns that aid is not reaching people facing famine, but the civil aviation head said no such flights had yet left the capital. Ethiopia"s government has been battling the Tigray People"s Liberation Front since November and thousands of civilians and an unknown number of combatants have since been killed. Last week, government forces said they had withdrawn from the Tigray capital of Mekelle, but the TPLF said its forces seized the city, a major shift in the conflict. read more Prime Minister Abiy Ahmed"s government declared a unilateral humanitarian ceasefire and said its soldiers left Mekelle to tend to greater security threats elsewhere. "Since Monday July 5, 2021, the Federal government has granted flight permission for all interested parties to provide humanitarian services in Tigray region," authorities said on Twitter. But Wesenyeleh Hunegnaw, director-general of the Ethiopian Civil Aviation Authority, said no such flights had taken off from Addis Ababa this week. "It (permission) has to be processed by the Ministry of Foreign Affairs and then has to come to us. So far, we have received nothing from MFA," he told Reuters. "And no flight has departed from Addis Ababa to Mekelle. If there were any, I would know." The UN humanitarian agency OCHA told Reuters in a brief statement that it welcomed the Ethiopian government"s announcement. "Unfortunately, no flights have yet been able to travel directly from Addis Ababa to Mekelle or (the northern town of) Shire this week," OCHA"s Guiomar Pau Sole said. "However, we are following up with all relevant actors to ensure that direct flights are able to operate as soon as possible, in light of this announcement." The United Nations said on Friday shortages of food had worsened dramatically over the past two weeks and some 400,000 people in Tigray were now estimated to be in famine, with another 1.8 million on the brink of famine. read more Also on Friday, the government denied blocking humanitarian aid to Tigray and said it was rebuilding infrastructure amid accusations it is using hunger as a weapon. It was not immediately possible to reach the TPLF or any of the Tigray region"s leaders for comment. Last week, a spokesperson for the TPLF condemned the government’s shutdown of services, including air transport, as a continued act of war. Pressure is building on both sides to end hostilities so that aid can reach the starving. The commander of the Tigrayan forces on Tuesday called for a negotiated ceasefire with the government and a political solution, saying the government could not win the war. read more Aid agency Medecins Sans Frontieres (MSF) on Wednesday called for an investigation into the deaths of its three employees killed by unknown assailants in Tigray last month. MSF said it was pulling back its activities in Abi Adi, Adigrat and Axum, in central and eastern Tigray, while it will continue to provide assistance to people in urgent need in other areas. "At this terrible time, we have made the extremely painful but necessary decision to suspend our activities in several areas of Tigray," MSF operations director Teresa Sancristoval said in a statement. Reporting by Dawit Endeshaw; writing by Omar Mohammed; editing by Maggie Fick and Nick Macfie