Comedian Paul O'Grady suffered a heart attack three years ago

The presenter of The New Paul O'Grady Show was admitted to hospital on Friday morning. His friend said: "It does appear he has had a heart attack."

The 51-year-old comedian suffered a heart attack in April 2002 and underwent an operation to widen a blocked artery.

A Channel Four spokeswoman said: "We are shocked and concerned by the news."

She added: "Along with Paul's many fans we are wishing him all the very best."

A spokeswoman for the William Harvey Hospital in Kent declined to comment.

After his heart attack in 2002, O'Grady said he was reviewing his lifestyle and giving up smoking.