The Hollywood star paid tribute to his former co-star after Jeff’s death was announced yesterday.
The two actors starred alongside each other in cult classic Grease in 1978.
John played the iconic role of Danny Zuko , which turned him into an international star, while Jeff appeared as one of his ‘T-Bird’ gang members.
“Jeff Conaway was a wonderful and decent man, and we will miss him. My heartfelt thoughts are with his family and loved ones at this very difficult time," John told American publication E! News.
Jeff died aged 60 after his family decided to take him off life support following doctors’ advice that the situation was “hopeless”.
The actor had been in a medically induced coma after he was found unconscious at his home earlier this month.
Celebrity Rehab star Jeff had fallen ill with pneumonia and sepis while recovering from recent back surgery.
He had also been struggling with alcohol and drug addiction.
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