Sir Frank Williams, who built the Williams team into one of the most successful in Formula 1, is in a stable condition after going into hospital.
The 78-year-old and daughter Claire stepped away from Williams earlier this year after its sale to US investors.
"Frank's medical condition is a private matter and therefore the family will not be releasing any further details at this time," read a statement.
Williams spent some time in hospital with pneumonia in 2016.
He has used a wheelchair since a car crash in France in 1986.
During his time with Williams, the team won nine constructors' championships and seven drivers' titles, and dominated much of the 1980s and 1990s.
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