NAIROBI, Jan 7 (Reuters) - An air strike hit a refugee camp in northern Ethiopia"s Tigray region, killing three Eritrean refugees, including two children, the United Nations said on Thursday. The strike on Wednesday hit Mai Aini refugee camp near the southern Tigrayan town of Mai Tsebri, the United Nations said. "Three Eritrean refugees, two of them children, were killed," the United Nations High Commission for Refugees (UNHCR) head Filippo Grandi said in a statement, adding that four other refugees were injured. The United Nations did not specify who carried out the strike but only the Ethiopian government has air power in the area. Government spokesperson Legesse Tulu and military spokesperson Getnet Adane did not immediately respond to requests for comment. The government has previously denied targeting civilians. At least 146 people have been killed and 213 injured in air strikes in Tigray since Oct. 18, according to a document prepared by aid agencies and shared with Reuters. The document was based on evidence collected by regional aid workers as well as witness testimonies, according to two of its compilers. It records 41 air strikes, with the deadliest being on Dec. 16 strike in the town of Alamata that killed 38 and wounded 86. It did not say how many of those killed were civilians and Reuters could not independently verify the figures. The 14-month-old war in northern Ethiopia between the federal government and the Tigray People"s Liberation Front (TPLF), who used to dominate Ethiopian politics, has killed thousands of civilians and displaced millions. Last month, Tigrayans forces withdrew from neighbouring regions, which they had invaded in July. Air strikes on the Tigray region have continued and the United Nations says no humanitarian aid is able to enter the region. About 150,000 Eritrean refugees live in Ethiopia and some have been targeted by belligerents on both sides of the conflict and cut off from aid for months at a time. A Reuters investigation in November revealed that Eritrean refugees had endured targeted killings, gang rapes and looting by both the TPLF and Eritrean forces, who entered the conflict on the side of the Ethiopian federal government.