Two men charged over the shooting of a policeman and attacks on the family of slain underworld figure Carl Williams may have links to Williams' killer Matthew Johnson.

Oak Park 24-year-old Rodney Phillips and Morwell 22-year-old Sam Liszczak were arrested and charged on Tuesday, two weeks to the day since Constable Ben Ashmole was shot in the head during a car intercept in Moonee Ponds.

Both men are linked to Johnson, who was convicted in 2011 of Williams' murder in Barwon Prison, and Tommy Ivanovic​, who was in the room at the time Williams was killed.