LONDON, May 9 (Reuters) - Britain's ITV said its advertising revenue would jump by around 12% in the second quarter, four times the level achieved in the first, boosted by the Euros soccer championship which kicks off in June.

The company, which broadcast "Mr Bates vs The Post Office" in January, on Thursday reported a 6% drop in total external revenue in the first quarter to 727 million pounds ($908 million).

($1 = 0.8006 pounds) (Reporting by Paul Sandle; Editing by Kate Holton)