Michael Douglas' imprisoned son has reportedly pleaded guilty to a new drug charge.

Cameron Douglas - who was sentenced to five years in prison in April after he pleaded guilty to possession and dealing methamphetamine and cocaine - entered the plea to a narcotics possession charge and has agreed to serve an additional year in jail.

He admitted yesterday (19.10.11) that he managed to get drugs in prison while serving his sentence.

The 32-year-old man is believed to have owned up to possessing drugs from May through to last week after illegal substances were found in his cell.

Following his admission, Federal Judge Richard Berman questioned the security at two federal prison facilities.

At Cameron's trial in April - which was attended by Michael and his ex-wife Diandra Douglas - he was given half of the 10-year sentenced he faced and credit for eight months already served.

The DJ and actor told the court of a wish to turn his life around and become an "entertainer".

He explained: "I apologise to my family and my loved ones for putting them through this nightmare of my making.

"I ask for an opportunity to be a role model to my younger brothers and sisters."