Betty Moffitt, the mother of American tennis player Billie Jean King, has died in Prescott, Arizona at the age of 91.

In a statement, King's publicist said that Moffitt passed away on Friday at home with her children by her side.

Born Betty German on May 26 1922, in Taft, California, she married Bill Moffitt and raised their two children in Long Beach, California, where they lived for more than 40 years.

The 39-time Grand Slam winner announced on Wednesday that she would not attend the opening ceremony of the Sochi Winter Olympics with the US delegation because of her mother's failing health.