The Belgium international midfielder who was also the subject of an offer from Manchester United earlier in the transfer window will join in time for Tottenham's Premier League fixture this weekend subject to completing a medical.
Dembele, 25, had entered the last year of his contract at Craven Cottage. His transfer in the first of a series of moves planned by Tottenham to reinvest their income from the sale of Luka Modric to Real Madrid.
Though the club's new manager, Andre Villas-Boas, had asked for some of Tottenham's recruitment budget to be spent on Joao Moutinho, the Portugal midfielder is understood to have been declared too expensive. The club is continuing to negotiate deals for France goalkeeper Hugo Lloris and Brazil attacking midfielder Willian, among others.
Meanwhile, Manchester City have stepped up their interest in the versatile France international Loic Remy as the Premier League champions seek to strengthen their attack ahead of Friday's transfer deadline. The club have informally asked Marseille to price the 25 year old, who can play either as a central striker or on the right wing.
Should a deal be concluded Remy would be brought in to Roberto Mancini's squad as a replacement for Adam Johnson, who was allowed to leave for Sunderland earlier this month after expressing his dissatisfaction at a lack of playing time.
He also represents an alternative option to buying Scott Sinclair from Swansea City, offering the kind of extensive experience of Champions League football that the England Under 21 international lacks.
Though Sinclair has been left out of the starting line-up for Swansea's two opening Premier League victories after refusing to extend his contract there, the Welsh club are yet to accept an offer for his transfer.
"We haven't actually agreed any deal with Man City at the moment," said Huw Jenkins, the Swansea chairman, yesterday. "I would have thought if they really wanted to sign Scott Sinclair they would have dealt with it a little bit better than they have. But that's their business.
"But it has dragged on too long and I hope one way or another it will be concluded the next couple of days."
Marseille would accept an offer of £15m for Remy, who has scored 37 goals during his two full seasons and has also attracted attention from Tottenham and Newcastle United.
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