TennisTim Henman has warned that increasing betting in tennis could risk the integrity of the sport.

Henman, 33, the former world number four, said in an interview with BBC television's Inside Sportprogramme broadcast last night that he has heard of players being asked to influence the outcome of matches.

"I personally have never experienced it but, listening to the players talking, it seems it goes on," said Henman.

"We've got to be very careful, very vigilant about it as tennis doesn't want to be associated with that."

Henman's comments come a month after the ATP began investigating possible irregular gambling patterns on a match at the Sopot Open in Poland between world number four Nikolay Davydenko and Martin Vassallo Arguello of Argentina.