"Very happy to join Spurs for the next five years," the midfielder wrote on his official Twitter account. (@MoussaSissoko)
Sissoko, who represented France in the final of the European Championship earlier this summer, spent three seasons with Newcastle after joining from Toulouse in 2013, and was relegated with the north-east club last season.
Earlier, Tottenham signed Olympique de Marseille forward Georges-Kevin Nkoudou on a five-year deal, with Clinton N'Jie going the other way on a season-long loan.
The 21-year-old Nkoudou, a France youth international capped to under-21 level, scored five goals in 28 league games last season as Marseille finished 13th.
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"#NkoudouSigns but I'm 40 years old now so I'm not sure to be as quick as I used to be," Nkoudou joked on his Twitter account after the protracted negotiations between the clubs finally ended on transfer deadline day.
Cameroon international N'Jie, 23, joined Spurs from Olympique Lyonnais in August last year but suffered with injury and featured only eight times in the league last season.
Tottenham, who have five points from three games, next visit bottom club Stoke City on Sept. 10.
(Reporting by Ian Rodricks in Bengaluru; Editing by Ken Ferris)
