BAGHDAD (Reuters) - Iraqi Shi’ite militias illegally detained villagers near the Islamic State-held district of Hawija in northern Iraq and subjected them to torture and ill treatment, Human Rights Watch said on Thursday.

The leader of one of the militias, which are known as Popular Mobilisation Forces (PMF), denied the accusation and said their fighters were strictly following the law in their dealings with civilians fleeing military operations in the area.

Iraq launched an offensive on September 21 to dislodge Islamic State from Hawija, which lies west of the oil city of Kirkuk and is one of two areas of the country still under the control of the militants.

Men from villages near Hawija were detained by militias from the Badr Organisation, a pro-Iran, Shi’ite grouping that is playing a major role in Baghdad’s war against Islamic State, and were taken to an unknown location, the HRW report said, based on interviews with villagers evacuated to a nearby refugee camp.

The villagers told HRW they had seen militia fighters using their gun butts to beat the detained men. During their detention the fighters brought them food only once and only a small amount of water but did not let them use a bathroom.

“Human Rights Watch has documented that PMF groups, including units affiliated with the Badr Organization, have screened, detained, and tortured people during the military operations,” said the report.Women were also detained briefly by Iraqi security forces and were questioned about their male relatives’ activities before being transported to the refugee camp, HRW said.

“While Iraqi forces do need all the help they can get, the government should not allow abusive forces to use this opportunity for even more abuse,” said Sarah Leah Whitson, Middle East director at Human Rights Watch.

The Iraqi government was not immediately available to comment on the HRW report, but local Badr commander Kareem al-Mohammedawi denied that villagers’ rights had been abused.

“We are strictly ordering our fighters to abide by the law and avoid mistreating refugees fleeing the fighting. But when we suspect someone is a terrorist we normally arrest him and hand him over to the security forces,” he said.

Hawija and a stretch of land along the Syrian border are the last pieces of Iraq still in the hands of Islamic State, which overran about a third of the country in 2014.