Islamic State jihadists are forcing children and disabled people into explosives-laden trucks and making them drive at Iraqi security forces in Mosul, a general from the U.S.-led coalition has said, according to AFP.

The barbaric tactic, coupled with other increasingly desperate battlefield measures, is a sign the IS group knows defeat is inevitable, officials say.

The jihadists have used exploding trucks, known in military circles as VBIEDs -- vehicle-borne improvised explosive devices -- and pronounced "Vee-Bids," to devastating effect in numerous engagements during the Mosul offensive and elsewhere in Iraq.

Speaking to AFP and other reporters in Baghdad this week, US Air Force Brigadier General Matt Isler said the IS group had adopted coercive new techniques in its use of suicide car bombs because the jihadists appear to be running out of willing drivers.

"We saw people being led to a VBIED, being put in (it) and being chained in the VBIED," he said.

"We've seen children put in VBIEDs as drivers, people that aren't able to walk... I don't know if they signed up for this service."

The coalition has often seen VBIEDs depart on missions, only for their drivers to veer off course and attempt to hide behind structures.

"We see a VBIED going to its attack, going off and hiding," Isler said.

"We see a party going to find the AWOL VBIED driver, we see (IS) command and control trying to figure out where their VBIED driver's gone, we've seen multiple VBIED drivers going AWOL."

The coalition first saw drivers being chained into trucks when Iraqi security forces approached the Tigris river as they cleared eastern Mosul, Isler said.