Mr Berlusconi has faced corruption charges in the courts for many years but has always protested his innocence.[Wethinks he doth protest too much here. The word the reporter meant was probably "maintained." English. It's tricky, even if you are English.] <--- Pretend we never typed that.
This just in! Barry L., who never misses a thing, reminds us that protest has additional definitions.
Here is No. 4, from Encarta's dictionary: 4. transitive and intransitive verb say firmly that something is true: to state or affirm something in strong or formal terms
He continued to protest his innocence.