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Bret Michaels, pictured here in January, was rushed to hospital on Thursday night after complaining of a severe headache. ((Jason Merritt/Getty Images) )

A new message has been posted on singer and reality star Bret Michaels's website revealing that doctors are still trying to locate the source of bleeding in his brain.

"At this point Bret remains in ICU in critical condition. He is under 24 hour doctors' care and supervision. We are hopeful that further tests will locate the source of the bleeding, which has still not been located. As we all know Bret is a fighter and we are hopeful that once all is complete the slurred speech, blurred vision and dizziness, etc. will be eliminated and all functions will return to normal," said the message posted on Sunday.

The message also thanked fans and friends for their support.

On Saturday, Joann Mignano, Michaels's publicist, confirmed the Poison frontman, who is currently on the TV series The Celebrity Apprentice, had to be rushed to hospital on Thursday night after complaining of a severe headache.

His condition is listed as a subarachnoid brain hemorrhage, or a brain bleed.

The 47-year-old reality TV star had an emergency appendectomy only last week after complaining of stomach pain.

Michaels, who is also a diabetic, wrote on his website that the surgery "has taken its toll."

Before joining The Celebrity Apprentice this season, Michaels was the star of VH1's reality dating series Rock of Love from 2007 to 2009.