The Daily Mail says Defoe was paraded in front of Tottenham supporters as their new signing on Tuesday night even though they had not agreed a fee with Portsmouth.
Pompey officials were stunned when Spurs went ahead with the ostentatious entrance just minutes before the Carling Cup semi-final first leg against Championship side Burnley.
The two clubs have yet to reach an agreement over the size of the transfer fee and negotiations will continue today.
Although Defoe has already agreed personal terms for his move back to White Hart Lane, he has not signed the £60,000 a week five-year contract and it has not been registered with the Premier League.
Portsmouth do not want to jeopardise the deal to sell the player, but they were furious when he was allowed to appear for a half-time interview with ITV as a Tottenham player.