"It is not a good day for Europe because Great Britain represented a lot in Europe both from the political, military point of view and from the perspective of scientific research and finance," said economist Romano Prodi, a two-time former prime minister of Italy who also served as president of the European Commission, reported Xinhua news agency.
"I am certain they will have problems and that they will be back in 15 to 20 years," Prodi added in televised comments on the sidelines of an event to celebrate the 110th anniversary of the founding of the General Confederation of Italian Industry Confindustria in the northern city of Turin.
Confindustria President Vincenzo Boccia was more optimistic.
"Brexit could be a great opportunity for Italy to attract investors who need to tackle the European market," Boccia told Italian news agency ANSA on the sidelines of the same event.
"Italy could become a great hub" as its geographically strategic position between Europe and the Mediterranean could also become a "geo-economic" one, Boccia said.
Former interior minister Matteo Salvini, leader of the far-right and eurosceptic League party, expressed his satisfaction.
"All the doomsday prophets who forecast economic catastrophes have been disproved, the British people have shown pride, courage and vision, their politic have respected the will of the people," Salvini tweeted.
Nicola Zingaretti, the leader of the centre-left Democratic Party that currently governs Italy in coalition with the Five Star Movement, saw Brexit as a defeat.
"From today the UK is out of the EU and we cannot but start from this realisation because after over 70 years, the process of integration not only suffers a blow ... but we are witnessing a return to the past," Zingaretti said at an event celebrating the 10th anniversary of ItaliaCamp, which describes itself as an "organisation that develops processes of innovation and social transformation".
That process "managed to unite hundreds of millions of people" without firing a shot, in the name of peace, jobs and culture, Zingaretti said at the event that also saw Prime Minister Giuseppe Conte among its featured speakers.
"We must react speedily to Brexit in order to bring that process (of integration) into the future," Zingaretti said.
While he did not comment on Brexit in his speech on Saturday, Conte tweeted just before midnight on Friday that the "UK leaves the EU family, but remains a strategic partner and friend. Let's work on an ambitious new partnership between the EU and the UK, for the stability and prosperity of our common destiny, in the interest of our citizens and companies."
According to Antonio Villafranca, co-head of the Europe and Global Governance Center at the Italian Institute for International Political Studies (ISPI), an independent think tank based in Milan, Brexit could cause tensions between Italy and the rest of the EU.
"We are already hearing about tariffs, about our parmigiano, our prosecco," Villafranca told RAI News 24 public broadcaster in an interview on Saturday in reference to Italy's prized cheese and sparkling wine.
"This could fragment European unity and we must avoid this at all costs, because it would diminish the negotiating power we (Italy) have in the negotiation with London," Villafranca said.
In an analysis released hours before Brexit went into effect, ISPI said that "compared to the other major EU countries, Italy appears to be less exposed to the hard Brexit risk: just 5 percent of our exports are directed to the UK."
However, Italy has the third largest trade surplus in Europe towards the UK at 12 billion euros a year (13.3 billion U.S. dollars), while the UK is the fifth-largest (European) importer of Italian goods.
The major Italian exports to the UK are industrial equipment, textiles, chemicals, and food products, according to ISPI.
( With inputs from IANS )