LOS ANGELES (Reuters) - There is no "sex tape" involving pop star Britney Spears and estranged husband Kevin Federline, his lawyer said on Tuesday. After Spears filed for divorce from the fledgling rapper this month, reports surfaced in the tabloid press that Federline had in his possession a videotape of the couple having sex and was considering making it public. "There is not a sex video of Kevin and Britney in existence," said Federline's divorce lawyer, Mark Vincent Kaplan. Representatives for Spears had no immediate comment. "It goes without saying that the stories of Kevin attempting to sell such a...