Addis Ababa - The United Nations human rights chief expressed concern on Tuesday over the deaths of at least seven people chanting anti-government slogans during a religious festival in Ethiopia last week.The unrest in the city of Woldiya in the northern Amhara region was the latest bloodshed to occur since widespread anti-government protests began in Ethiopia in 2015 that have killed hundreds and posed one of the biggest challenges to the ruling party's 27 years in power.The deaths in Woldiya occurred during the Ethiopian Orthodox Church's Timkat celebration of Jesus Christ's baptism, a two-day festival where replica Arks of the Covenant are paraded through the streets and people baptised en masse.Ravina Shamdasani, spokesperson for the High Commissioner for Human Rights, said the deaths occurred when security forces allegedly shot people chanting anti-government slogans. She added the UN was "concerned by the use of force by security officials against worshippers"."This incident is all the more regrettable, as it comes just two weeks after Ethiopia's ruling coalition, the Ethiopian People's Revolutionary Democratic Front, officially announced its intention to undertake reforms," Shamdasani said."We call on the authorities to ensure that the security forces take all feasible measures to prevent the use of force."Earlier this month, Prime Minister Hailemariam Desalegn announced Ethiopia would release some jailed politicians. So far, hundreds of prisoners have been freed, though most of the country's most notable detainees remain behind bars.The demonstrations against the ruling coalition started in 2015 when Ethiopia's largest ethnic group, the Oromos, protested a proposal to expand the boundaries of the capital Addis Ababa, that they claim would have deprived them of their land.They were soon joined by the Amharas, the country's second-largest ethnicity who predominate Woldiya and have long complained of marginalisation.In October 2016, the government imposed a state of emergency that lasted 10 months as a way to stop the unrest, but protests and deaths have occurred sporadically in the Oromo and Amhara federal states since it ended.