The United Nations rights office has urged Iraq to immediately halt all executions, stressing that putting to death 38 terrorist suspects was “deeply shocking.” "We are deeply shocked and appalled at the mass execution” at a prison in the southern city of Nasiriyah on Thursday, United Nations human rights office spokeswoman Liz Throssell told reporters in Geneva. “It appears extremely doubtful that strict due process and fair trial guarantees were followed in these 38 cases," Agence France Presse quoted Throssell as saying on Friday. The UN has learned of 106 executions in Iraq so far this year, including mass-hangings of 42 people in September. "We once again urge the Iraqi authorities to halt all executions, establish an immediate moratorium on the use of the death penalty and carry out an urgent and comprehensive review of the criminal justice system," Throssell said. Dakhel Kazem, a senior official in the provincial council, said the prison executed "38 death row prisoners belonging to Al-Qaeda or ISIS accused of terrorist activities". A prison source told AFP that those executed on Thursday were all Iraqis, but that one also held Swedish nationality. Sweden had confirmed that among them was an Iraqi-Swedish citizen. "The death penalty is an inhumane, cruel, and irreversible punishment. Sweden and the rest of the EU condemn its application in all its forms," Swedish Foreign Minister Margot Wallstrom said in a statement.  Sweden on Friday summoned Iraqs ambassador over the mass-hangings. Throssell also voiced deep concern over the reported shelling and burning of homes in the Iraqi city of Tuz Khurmatu, warning of a "serious risk" that violence could escalate. The United Nations rights office pointed to reports that residential areas of Tuz Khurmatu, in the Salahaddin governorate, had been shelled on December 9 and 12, "causing casualties among civilians." "It is not clear who is carrying out the shelling, which is reported to be coming from the mountains overlooking the area," Throssell told reporters. Iraqi forces are working to determine where the shelling is coming from and who is responsible. Tensions have been swelling in the disputed area of Tuz Khurmatu following Septembers independence referendum in the neighboring Kurdistan Region.  The citys population is a mix of Turkoman, Kurd and Arab communities, and Throssell warned that "there is a serious risk that given the ethnic and religious fault lines in the area, that violence could escalate and spread." In recent weeks, clashes have raged between the Kurdish security forces also known as the Peshmerga and Turkmen Popular Mobilization Units (PMUs).  "This fighting has to date resulted in an unconfirmed number of deaths in each group," Throssell said. She said staff from the UN rights office visited the city on December 7 and again on the 14th to investigate reports of the burning of homes and looting of businesses. They had seen "some 150 premises that had been burned or otherwise damaged," she said, adding that they had also spoken with people who had fled violence in the city and were currently staying in Kirkuk and Erbil. In October, a similar number of houses were reportedly looted and burned by Turkmen PMUs and civilians, she pointed out. As many as 11 houses reportedly belonging to Kurdish families and officials had also been destroyed by explosives in the city, Throssell said. "Thousands of residents, mainly of Kurdish origin left for the Kurdistan Region of Iraq, apparently fearing repercussions, and to date many have not returned," she warned. The UN rights office called for an end to "all acts that threaten the fundamental rights of the Tuz Khurmatu population."  "We also call on the Iraqi authorities to ensure that civilians there are protected and those responsible for human rights abuses brought to justice," Throssell said.