LONDON, Feb 21 (Reuters) - The odds of Britain leaving the European Union shortened on Sunday after reports that influential London mayor Boris Johnson would back the 'leave' campaign, bookmaker Ladbrokes said.
The bookmaker said the odds of a British exit had improved to 2/1 from their previous price of 12/5. Johnson had also become favourite to be the next leader of the Conservative Party when Cameron decides to step down, they said.
The BBC reported Johnson's decision to back a British exit from the bloc at a June 23 referendum without citing sources ahead of an official announcement expected around 1700 GMT. One source with knowledge of the decision confirmed to Reuters that he would back the 'out' campaign. (Reporting by William James; editing by Guy Faulconbridge)