World No.1 Lleyton Hewitt has reportedly threatened international men's tennis organisation ATP with legal action over a record fine for failing to attend a TV interview last year.

Sydney's The Daily Telegraph newspaper said Hewitt was demanding almost $A2.5 million in damages to his reputation and legal costs.

The report said lawyers acting for Hewitt told the ATP proceedings would be issued in the South Australian Supreme Court in June unless the matter was resolved.

Hewitt was fined $US106,000 ($A176,000) - the largest ever levied on an Australian sportsman - by the ATP last August for failing to show for an interview with US network ESPN in Cincinnati.

The fine was reduced to $US20,000 ($A33,100) on appeal in January.

The report said the basis of 22-year-old Hewitt's claim was that the ATP acted unlawfully in withholding his prizemoney in Cincinnati where the Australian reached the final.

The report said Hewitt alleged the ATP breached its contract with him, defamed him in media statements and "intentionally and without justification" interfered in his business affairs.

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