The 23-year-old Chadli, who will discuss personal terms and undergo a medical with the Barclays Premier League club, has spent three seasons in the Eredivisie with Twente and scored in both Champions League ties against Spurs during the 2010-11 season.
If the deal is completed without a hitch the winger will join his new team-mates in Hong Kong, where Andre Villas-Boas's side will compete in the Barclays Asia Trophy.
Chadli has 14 international caps after initially representing Morocco in a non-competitive fixture before deciding to turn out for Belgium.
He made a name for himself at AGOVV Apeldoorn before enjoying a successful spell in Holland, scoring 31 goals for Twente and prompting Spurs to make their move - with the transfer fee reported to be around £7million.
He is likely to become Villas-Boas' second major acquisition of the summer following the signing of Brazil international midfielder Paulinho from Corinthians earlier this month.
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