New York, Sep 14 (DPA) Serena Williams was handed a $10,500 fine Sunday for the obscene outburst against a lineswomen that got her defaulted on a point penalty from her US Open semi-final Saturday against Kim Clijsters.

'The maximum permissible on site fine of $10,000 has been levied for unsportsmanlike conduct against Serena Williams for her on-court behaviour during the women's semi-final,' read a statement from US Open officials.

'Ms Williams also will be fined $500 for racket abuse, which took place at the end of the first set of the same match.'

Williams was accused of threatening the lineswoman, who called a foot fault that gave a match point to Clijsters in their drama-packed semi.

Williams later refused to apologize for the incident.