Vandross won four Grammys in the 1990s

The Grammy-winner is in a "critical but stable" condition in hospital in New York after falling ill on 16 April.

But he has shown positive signs of improvement, spokeswoman Lois Najarian has said.

"The neurologists just feel that he's been extremely responsive over the course of the last day," she said on Wednesday.

Vandross, who turned 52 on Sunday, fell ill at his home in Manhattan.

It had been reported that the singer was conscious after suffering the stroke.

Ms Najarian said Vandross had been in good health before the stroke.

Star producer

Vandross, who has sold more than 20 million records worldwide since pursuing his solo career, won four Grammy awards in the 1990s.

His hits include Jump to It, Here and Now, and Don't Wanna Be a Fool.

Apart from his own singing and writing, he has produced for stars including Aretha Franklin, Dionne Warwick, Diana Ross and Whitney Houston.

Vandross has battled weight problems and admitted once hitting the scales at well over 300 pounds.

He has also suffered from hypertension and diabetes.

"If I'm emotionally distraught, then eating is my coping mechanism", he told Britain's Q magazine in 1991.

He said in 2001 that he was planning to write a book about his most successful attempts to shed weight.