Kurdish forces have found the remains of about 25 members of the Yazidi minority killed by the Islamic State jihadist group in a mass grave in northwest Iraq, officials said Monday.

"Peshmerga forces discovered a mass grave yesterday (Sunday) containing the remains of about 25 people -- men, children and women -- from the Yazidi (sect) who were killed by" IS jihadists, local official Myaser Haji Saleh told AFP.

A peshmerga lieutenant colonel said the grave was found near Sinuni during a search for explosives that IS often leaves behind, posing a threat to security forces and civilians even after they withdraw.

"Our forces were searching for explosives and mines planted by (IS) in the area and found the grave during the search," the officer said.

Some of the victims had been shot dead and others "slaughtered" using knives, he said.

IS spearheaded a June offensive that began in the northern province of Nineveh, where the mass grave was discovered, and overran large areas north and west of the Iraqi capital.

After sweeping south towards Baghdad, the militants again turned their attention to the north in August, driving Kurdish forces back toward their regional capital and seizing areas including Sinuni.

IS carried out a campaign of killings, kidnappings and enslavement against Yazidi Kurds living in the area that the UN termed an "attempt to commit genocide."

Backed by US-led air strikes and assisted by international trainers and advisers, Kurdish forces have made significant gains in the north.

Federal troops, Shiite militiamen and Sunni tribesmen have also pushed IS back farther south, but significant territory, including three major Iraqi cities, remains in the hands of the jihadists.