The body of British-born Panathinaikos and Greek defender George Baldock was found in a swimming pool at his home in the southern Athens suburb of Glyfada on Wednesday, police sources told Reuters.

The cause of death remained unknown.

Police attempted cardiopulmonary resuscitation on the 31-year-old former Premier League player but were unable to revive him and emergency medical units confirmed his death, a police official said.

Baldock, who was of Greek descent and won 12 caps, moved to Panathinaikos from Sheffield United in May after the English side were relegated from the top flight.

“Sheffield United Football Club is shocked and extremely saddened to learn of the death of former player George Baldock,” the club posted on social media.

“The defender left the club in the summer after seven years at Bramall Lane and was extremely popular with fans, staff and team-mates who wore a red and white jersey alongside him. Our sincere condolences go out to everyone associated with Sheffield United.” George's family and friends.

Baldock also played for lower leagues MK Dons and Oxford United.

Information from Reuters contributed to this report.