ADDIS ABABA—An Ethiopian government air strike on the capital of the northern Tigray region on Friday forced a U.N. aid flight to abort a landing there, the United Nations said. In neighboring Amhara region, people were fleeing intensified fighting. Humanitarian sources and the Tigray People’s Liberation Front (TPLF), which controls the area, said a university in the regional capital Mekelle was hit by the air strike. Government spokesman Legesse Tulu said a former military base occupied by TPLF fighters was targeted, and he denied the university was hit. Reuters was not able to independently confirm either account. TPLF-controlled Tigrai TV reported that 11 civilians were wounded in the air strike. It was at least the fourth day this week that Mekelle had been attacked. The United Nations suspended all flights to Mekelle after a U.N. plane with 11 passengers had to abort landing on Friday. The flight from Addis Ababa …