Barber has been appointed Chief Executive Officer at new Major League Soccer franchise Vancouver Whitecaps.
Daniel Levy, the Spurs chairman, told the club's website: "I should like to take this opportunity to thank Paul for his hard work, dedication and contribution to the growth and success of our commercial operations and for his support for the wider development of our Club during his time with us. I wish him every success when he takes up his new role in North America.
"Paul will take up his new position in the Spring of 2010. He will remain in his role of Executive Director progressing our new shirt sponsor and stadium naming rights discussions until the end of February next year. After this time, Paul will become a Non-Executive Director, helping to provide a smooth transition."