WASHINGTON — (CNN) ISIS has “executed” 232 people near the Iraqi city of Mosul and taken tens of thousands of people to use as human shields against advancing Iraqi forces, the United Nations says.

The terror group carried out the mass killings Wednesday, punishing people who had defied its orders, a spokeswoman for the UN human rights arm told CNN.

“ISIS executed 42 civilians in Hammam al-Alil, south of Mosul. Also on Wednesday ISIS executed 190 former Iraqi security forces for refusing to join them, in the Al Ghazlani base near Mosul,” said Ravina Shamdasani of the Office of the UN High Commissioner for Human Rights.

Since October 17, ISIS has taken tens of thousands of men, women and children from the outskirts of Mosul into the city.

Shamdasani said the United Nations feared the group intended “to use them as human shields against the Iraqi forces advance on Mosul.”

There have been other reports over the past week of civilians being killed as ISIS tries to herd people into its last major stronghold in Iraq and the nation’s second city against the Iraqi-led operation.

Reports of the latest ISIS atrocities came as Iraqi security forces reported further progress Friday in their advance from the south of Mosul.

Abdulrahman al Wagga, a member of the Nineveh provincial council, told CNN the security forces had taken the town of al Shura, about 30 kilometers (19 miles) south of Mosul, and had evacuated 5,000 to 6,000 civilians from there.

The area is being cleared of homemade bombs and booby traps, he said.

Iraqi security forces and federal police have also now “90% surrounded Hammam al-Alil,” the largest town south of Mosul, Wagga said.

Wagga said the Iraqi forces might storm Hammam al-Alil soon but it would depend on the situation on the ground since civilians were still present.

Reports indicate that ISIS has abducted at least 5,370 families from around al Shura and 150 more from around Hammam al-Alil, Shamdasani told a briefing in Geneva, Switzerland.

Another 160 families have reportedly been seized from around Qayyara, she said, and 2,210 families from the Nimrud area of Hamdaniya district.

“Forced out by gunpoint, or killed if they resist, these people are reportedly being moved to strategic locations where ISIL fighters are located,” Shamdasani said, using an alternative acronym for ISIS.

Information received by the United Nations suggests some 60,000 people are currently living in Hammam al-Alil, an ISIS stronghold with a previous population of 23,000, she said.

The use of human shields is banned under international humanitarian law, and constitutes a violation of the right not to be arbitrarily deprived of life, the UN refugee agency said.

ISIS has used the same tactic in previous battles in Iraq, notably in Falluja in June.

The UN High Commissioner for Human Rights, Zeid Ra’ad Al Hussein, also warned last week that ISIS fighters appeared to be “using civilians in and around Mosul as human shields as the Iraqi forces advance, keeping civilians close to their offices or places where fighters are located, which may result in civilian casualties.”

The United States and its allies have killed between 800 and 900 ISIS fighters in the operation to retake Mosul, US Army Gen. Joseph Votel said Thursday.

US military officials estimate that 3,000 to 5,000 ISIS fighters are defending Mosul, with an additional 1,500 to 2,000 ISIS soldiers in a zone outside the city.

The ISIS fighters face a 90,000-strong force of Iraqi government troops, Kurdish Peshmerga fighters and irregular militia soldiers — but have had plenty of time to prepare their defenses.

The militants are using a “scorched earth” policy by destroying houses, buildings and bridges to slow down the advancing Iraqi security forces, said Wagga, the local leader.