Howard, a keen cricket fan, was asked at a lunchtime meeting of party faithful on the New South Wales south coast on Friday if Muralitharan threw the ball when he bowled and he replied: "Yes."
"They proved it in Perth too, with that thing," he added, drawing an image of a video screen with his hands.
Muralitharan, the top Test wicket-taker of all time with 521 wickets, has a genetic defect which stops him fully straightening his bowling arm upon delivery.
Murali was reported for a suspect action by English match referee Chris Broad during the third and final Test of the March series in Sri Lanka won 3-0 by Australia.
Perth-based biomechanics experts subsequently tested him and initially found he straightened his bent arm by 14 percent in bowling a delivery tagged the doosra.
The 'doosra' is a delivery which spins away from right-handers instead of coming into them like a normal off-break.
Under remedial work Murali reduced the arm straightening to 10 percent, which is still twice the amount allowable for spinners under International Cricket Council (ICC) regulations governing illegal bowling actions.
After being reported to the ICC Muralitharan has been ordered to stop bowling his "doosra" or face being suspended for up to a year.