Star Trek actor Leonard Nimoy has revealed that he is suffering from a progressive lung disease known as "chronic obstructive pulmonary disease."
The 82-year-old star attributed the illness to smoking, even though he quit the habit 30 years ago.
Taking to Twitter, Leonard said: "I quit smoking 30 yrs ago. Not soon enough. I have COPD. Grandpa says, quit now!! LLAP (Long Live and Prosper)."
The actor, best known for his iconic role as the highly logical Vulcan crew member of the SS Enterprise Mr Spock, was spotted in a wheelchair in New York late last month.
Despite his frail health the much-loved actor has continued to work and starred as Dr. William Bell in the hit science fiction thriller Fringe until 2012.
He made a cameo appearance as Mr. Spock in last year's Star Trek sequel Into Darkness, starring Chris Pine.
The actor retired from attending Star Trek conventions in 2011 but continues to be an avid champion of the cult TV series and urged his fans to tune into a forthcoming marathon of shows being shown on US television next month.
Chronic obstructive pulmonary disease hampers breathing and is said to be caused by smoking.