Michael Douglas desperately wants to see his imprisoned son.

Speaking at the Emmy Awards on Sunday - after giving a "shout out" to Cameron during his acceptance speech for winning Lead Actor in a Miniseries or Movie - Michael took aim at the American prison system.

He said: "If you happen to have a slip - this is for a prisoner who is non-violent - as about a half a million of our drug addicted prisoners are, they punish you.

"So for my son's case, he's spent almost two years in solitary confinement and right now I'm being told that I cannot see him for two years."

Cameron - Michael's son with ex-wife Diandra Luker - was handed a five-year sentence for heroin possession and conspiracy to distribute narcotics in 2009, which was extended by four and a half years in 2011 after he committed drug infractions behind bars. He has spent long stretches in solitary confinement, most recently in January when was found to have drugs in his body while serving time in a prison in Loretto, Pennsylvania.

Michael added: It's over a year now and I'm questioning the system. Obviously, at first, I was certainly disappointed with my son, but I've reached a point now where I'm very, very disappointed with the system."

Cameron is currently expected to remain in prison until early 2018. In a blog post earlier this year he claimed he is "trapped in a vicious cycle of relapse and repeat".