Grillo criticizes Parma mayor, one of his own M5S members
Relations soured over expulsions of dissident MPs
08 April, 16:50"Captain Pizza disagrees with the very rules that brought him to the mayor's seat," Grillo wrote on his blog.
Voted in as mayor in May 2012, Pizzarotti, 41, was the first candidate to bring the M5S to power in a large city. Movement leader Grillo often invited him to share the stage with him while on the campaign trail.
However, the once-close relationship between the two has soured in recent months over Grillo's expulsion of numerous dissident MPs. So far, 19 MPs have been either expelled or resigned from the M5S in protest.
The movement swept to a surprise victory in February 2013 parliamentary elections, with a total of 164 MPs elected in both houses.