Italy's 5-star leader Luigi Di Maio on Sunday said President Sergio Mattarella should be impeached for betraying the state because of his rejection of a eurosceptic as economy minister.

"We were a few steps away from forming a government, and we were stopped because in our cabinet there was a minister who criticised the EU," Di Maio said in an interview on RAI state television.

"I want this institutional crisis to be taken to parliament... and the president tried," he added, specifying the charges would made under article 90 of the constitution.

Under that article, the president would be voted on "for high treason or attacking the constitution" by all members of parliament. If a simple majority votes in favour, the constitutional court would then be called to decide whether to impeach or not.