LOS ANGELES -- A judge rejected a motion by Marion "Suge" Knight's attorney to restore the former rap mogul's visits with family and receive mail and phone calls while he awaits trial in a murder case.

Los Angeles Superior Court Judge William C. Ryan ruled Thursday that jail officials properly obtained an order earlier this year to restrict Knight's contact with the outside world to preserve jail security. Details about why the order was obtained remain under seal, but Ryan's ruling states it was done "to ensure institutional security" and not to punish the Death Row Records co-founder

Knight, 51, has pleaded not guilty to murder and attempted murder charges filed last year after he ran over two men outside a burger stand in Compton, California. He told a judge on April 21 that the restrictions were hampering his defence, which Ryan said was not the intention of the restrictions.

Knight's elderly parents are among those who have been unable to visit Knight since his visitation rights were rescinded in February. Ryan wrote that they can petition to visit their son and the request will be considered.

Knight's attorney Thaddeus Culpepper said he believes Ryan's order misstates the law.

"We're 100 per cent correct on the law," Culpepper said Monday. "Mr. Knight's pretrial constitutional rights continue to be violated without justification and without notice. We'll continue to do what's in Suge Knight's best interests going forward."

Culpepper's motion accused Ryan and other judges of conspiring to deprive Knight of his rights. Ryan rejected a request by prosecutors to sanction Culpepper, but the judge wrote the accusations were contemptuous and if similar conduct is displayed in the future, sanctions might be imposed.

"Counsel's representations are patently and demonstrably false and defamatory," Ryan wrote.

Knight was a key player in the gangster rap scene that flourished in the 1990s and has been kept under tight security since he turned himself in to authorities after the fatal altercation in January 2015. His lawyers have said Knight was acting in self-defence when he ran over Cle "Bone" Sloan, who was punching Knight through the window of his pickup truck, and also ran over Terry Carter, who died from his injuries.

Death Row Records label once listed Dr. Dre, Tupac Shakur and Snoop Dogg among its artists. Knight lost control of the company after it was forced into bankruptcy.

He faces potential life sentences if convicted because of prior convictions for armed robbery and assault with a gun.