03/11/2013 07:07 EDT | Updated 05/11/2013 05:12 EDT

Ricky Burns changes promoters to face possible lawsuit, end title unification lightweight bout

LONDON - WBO lightweight champion Ricky Burns is facing a possible civil lawsuit after switching promoters to force the cancellation of the unification bout against IBF holder Miguel Vazquez next month.

Burns was presented Monday as the newest fighter for promoter Matchroom, causing Frank Warren to claim a breach of contract and announce his intention to sue the 29-year-old Scot for "substantial damages."

Warren says "Burns is under binding promotional and management contracts."

Burns (35-2, 10 knockouts) hasn't fought since retaining his belt against Kevin Mitchell in September but had been due to fight Vazquez at Wembley Arena on April 20 in a postponed contest.

Burns says "I just felt over the last year or so things hadn't been working out" as "there were a few issues that needed working out."