Martin Sheen admitted it was ''painful'' to see his son Charlie Sheen have a public meltdown.

The 'West Wing' star has confessed he felt ''powerless'' to help the 49-year-old actor after he was fired from 'Two and a Half Men' in 2011 and participated in his infamous interview with ABC News' Andrea Canning, in which he claimed he wasn't bipolar but ''bi-winning'', following his axing from the CBS show.

Martin said: ''What he was going through at that time, we were powerless to do much. Except to pray for him and lift him up.

''You try to be as present as possible. But you have to be aware of the circumstances. You have to be aware of many things that the public is not aware of.

''Only those of us that knew him understood what was going on. I'm talking about steroids, at that time. He was in a very desperate situation. And he was doing what he felt would get him out of it - going public. And it was very painful. No less painful for him.''

The 74-year-old actor has a turbulent past of his own and was forced to quit drinking after suffering a heart attack on the set of his 1977 movie 'Apocalypse Now' because of his alcohol intake.

The 'Platoon' star added it was difficult to stand by and watch his son go through a similar plight.

He told Radio Times magazine: ''You can assure them you're there and you love them, but you cannot effect chance. That's your ego, for the most part. You pray for a moment of clarity, you trust in a higher power and you never, ever give up hope. Because that is a measure of despair.''