Iraqi forces have launched a broad offensive to retake the city of Hit from the Islamic State group in the western province of Anbar, a top commander said Saturday.

Led by the elite Counter-Terrorism Service, forces from the police, army and local tribal fighters were making a final push to retake Hit, 145 kilometres (90 miles) west of Baghdad.

"They have begun a broad operation to liberate Hit and Kubaysa," Major General Ali Ibrahim Daboun, the head of the Al-Jazeera Operations Command, told AFP.

Kubaysa is a smaller town a few miles west of Hit, a key hub along the Euphrates that the jihadists have controlled since October 2014.

Daboun said Iraqi security forces and tribal fighters had retaken a cement plant west of Kubaysa and raised the Iraqi flag there.

"Members of the terrorist Daesh (IS) gangs have fled back into the town centre," the head of the local council for Al-Baghdadi district, Malallah al-Obeidi, told AFP.

Daboun said Iraqi aircraft and jets from the US-led international coalition were providing air support.

Al-Asad military air base, which houses a large contingent of US and other foreign military advisers, lies around 35 kilometres northwest of Hit.

Iraq's security forces launched a final push against IS in Anbar's provincial capital Ramadi late last year and established full control over the city last month.

Aid agencies have voiced concern over the fate of an estimated 35,000 civilians who have fled Hit and its surroundings in the run-up to the latest military offensive.

The International Committee of the Red Cross said late Friday that thousands of freshly displaced people were stranded in areas where very little assistance is available.

The organisation said it was able to deliver aid for the first time on Friday to around 12,000 people west of Ramadi.

"We don't know how they managed to survive. Repeated access is crucial in order to help the remaining thousands of people who urgently need humanitarian aid," said Katharina Ritz, head of the ICRC delegation in Iraq.

IS still controls vast areas of Anbar province near the borders with Jordan and Syria, as well as the city of Fallujah, which is only 50 kilometres from Baghdad.