The spokesman for Iraq's elite counterterrorism forces says tens of thousands of trapped civilians have stalled Iraqi forces fighting the Islamic State group in the country's western Anbar province.

Iraqi forces re-launched an offensive on the town of Hit, 85 miles (140 kilometers) west of Baghdad, under cover of heavy coalition airstrikes early Thursday morning, Sabah al-Numan said.

The counterterrorism forces, who are leading the operation, reached within three kilometers of Hit city center before being forced to stop, al-Numan said.

Al-Numan said the forces "are making a plan to evacuate these families" and leaflets were dropped over Hit indicating which roads can be used to flee.

The town of Hit lies along an IS supply line linking the group's extremist forces in Iraq to those in Syria.