“Hashid forces have cut off the Tal Afar-Sinjar road,” Mohandis said on social media.
A Kurdish security official confirmed to AFP that Hashid forces had linked up with other anti-IS group forces, including Kurdish fighters, in three villages in the area.
The town of Tal Afar, which lies about 50 kilometres west of Mosul, is still under the control of the jihadists.
The IS group also remains in control of the road between Mosul and Tal Afar, Mohandis said. “This is what we are dealing with now,” the paramilitary leader said, implying that the militias will next try to separate Mosul from Tal Afar.
Iraqi forces launched a major offensive on October 17 to retake Mosul, which is the country’s second city and where jihadist strongman Abu Bakr al-Baghdadi proclaimed a caliphate in 2014.
The announcement that Mosul was virtually encircled came a day after the last major bridge over the Tigris in Mosul was bombed by the US-led coalition fighting the IS group.
Federal forces have already entered the city from the east. Kurdish peshmerga and other forces are also closing in from the north and south, while only the west had remained open before Wednesday.
Almost two and a half years after IS took over swathes of Iraq, forces backed by the US and other partners have regained much ground, but the greatest challenge still lies ahead.
Mosul is the last major prize in Iraq for the diverse and sometimes rival forces involved in the anti-IS effort, and the jihadists have offered stiff resistance there.
The eastern side of the city was expected to offer less resistance than the west bank, but elite forces from Iraq’s Counter-Terrorism Service (CTS) have struggled to make significant progress.
IS fighters moving in an intricate network of tunnels have used snipers, booby traps and a seemingly endless supply of suicide car bombers to stop Iraqi forces.
Authorities have not released casualty figures since the start of the offensive but fighters have admitted being surprised by how fierce the IS group’s resistance has been.
The intensity of the fighting has been one of the factors preventing civilians from fleeing to the safety of some of the camps being set up around Mosul.
The United Nations had expected around 200,000 people to flee their homes in the first few weeks of the offensive, but only about a third of that number had been displaced by Wednesday.
As they have inched their way through the city, fighting house-to-house, forces have been encouraging residents to remain in their homes.
Evacuating the population would allow Iraqi forces to use heavier artillery and achieve faster results but Iraq’s leadership wants to prevent the complete destruction of Mosul.