Italy's new president, Sergio Mattarella, assumed office with a ringing call to the nation to root out organised crime and corruption devouring public resources and solve a protracted economic crisis depriving young people of their future.

Mr Mattarella, whose elder brother, Piersanti Mattarella, was killed while governor of Sicily by the Mafia in 1980, denounced the "alarming" spread of the Mafia from its southern base to northern cities.

The 73-year-old head of state likened organised crime to "a pervasive cancer that destroys hopes ... and tramples rights".

Premier Matteo Renzi's government has appointed a special anti-corruption fighter.

"Corruption has reached an unacceptable level," said Mr Mattarella, who was serving as a constitutional court justice when lawmakers elected him to the nation's highest office on Saturday.

"It devours resources that could be devoted to the citizens. It impedes the proper carrying out of market rules" and "penalises the honest and capable".

Corruption is blamed for discouraging business start-ups and foreign investment.

Italy's economy has been mired in an economic crisis since 2008.

Mr Mattarella lamented that the prolonged slump "has wounded the social fabric of our country," created new poverty and "robbed the future from our young women and men".

He told Italy's oft-squabbling political class that national unity can "restore a horizon of hope to the country".

In his inauguration speech to Parliament he also pledged to use his seven-year term to encourage government-backed electoral reforms, including changing electoral laws in the hope of making governments more stable.

A former centre-left minister, Mr Mattarella said nations cannot combat "the terrible challenge of fundamentalist terrorism" with fortress mentalities but need a global response.

"The threat is much deeper and vaster. Under attack are the foundations of freedom, democracy, tolerance and co-existence," he said, recommending global responses.