Film star Michael Douglas has spoken for the first time since his son Cameron was sentenced to five years in prison for drug-dealing.

The Wall Street actor told NBC's Today programme that he hoped 31-year-old Cameron's time in prison would help him make a "fresh start".

Speaking frankly, he also took the blame for at times being a "bad father" to Cameron, who had been abusing drugs since he was 13 years old.

Cameron, whose mother is Michael's ex-wife Diandra Douglas, was given the jail term last month for dealing methamphetmine and possessing heroin.

"My son was a drug dealer, and he tried to kill himself for a while, and I can't condone his behaviour," said 65-year-old Michael.

"(But) with all the mistakes and the disease that Cameron has, he is a great young man and I wouldn't be supporting him if I didn't feel that way."