Kinshasa - The United States and European Union on Wednesday urged Congolese security forces to refrain from using "excessive force" after soldiers fired on Burundian refugees last week, killing over 30."The US government is dismayed by the violence and death of more than 30 Burundian nationals and a Congolese soldier in Kamanyola, in the eastern Democratic Republic of the Congo," State Department spokeswoman Heather Nauert said in a statement. "We urge the security forces of the DRC to refrain from using excessive force".According to Monusco, the UN's peacekeeping mission in the country, at least 36 refugees in Kamanyola, in the eastern province of South Kivu, were killed during violent clashes on Friday. A Congolese soldier also died.Government spokesman Lambert Mende claimed on Saturday that many of those killed were members of an "armed group".According to interior ministry official Josue Boji, the clashes began after a group of refugees overran a jail run by the country's domestic intelligence agency to demand the release of four Burundians who had been arrested for expulsion on Wednesday night.Boji said troops tried to disperse the refugees by "firing in the air but were overwhelmed" when the group responded by throwing stones. At least 124 refugees were wounded.The DRC government opened an inquiry into the deaths on Sunday."The cause of the violence must be determined and perpetrators must be held accountable," Nauert said.She added that the Congolese government should work with the UN refugee agency and UN peacekeepers "to ease tensions between Burundi refugees and their host population".In an earlier statement, the European Union's delegation in Kinshasa said Congolese soldiers "must respect international norms."Congolese security forces cannot resort to disproportionate force," it said.Tens of thousands of Burundians have fled to the eastern DRC to escape a wave of violence that unfurled in 2015 after Burundian President Pierre Nkurunziza sought a fiercely contested third term in office.Overall, the violence in Burundi has claimed between 500 and 2 000 lives, according to differing tolls provided by the UN or NGOs and more than 400 000 Burundians have fled abroad.