Boxing promoter Frank Warren has admitted that he is thinking about taking legal action against retired heavyweight fighter Mike Tyson.

The former US sportsman has claimed in his new autobiography Undisputed Truth that he took drugs before a number of fights, including his bout against Lou Saverese in June 2000, which was promoted by Warren.

"I haven't seen the book yet, but once I get a copy of it, our solicitors are looking at that and other things in the book," Warren told The Telegraph.

"We will wait and see, but it is obviously very concerning and if it is the case we'll be putting that to our lawyers."

Tyson also admitted in his book that he used a fake penis containing someone else's urine to prevent drugs from being detected.