BRITISH police had foiled a plot to kidnap Prime Minister Tony Blair's 5-year-old son Leo, The Sun newspaper reported today. Citing an unnamed security source, the tabloid newspaper said a group which campaigns for the rights of divorced fathers had planned to snatch the child and hold him for a short period. It said it had no details of how the group planned to carry out the kidnapping. A spokesmen for Mr Blair's office and London police had no immediate comment.