City of London should not suffer from Brexit - UK's Johnson

FLORENCE, Italy, Sept 15 (Reuters) - British Foreign Secretary Boris Johnson said on Thursday London's financial sector was a "massive asset" to the whole of Europe and should not be weakened by Britain's decision to leave the European Union.

At a news conference with his Italian counterpart Paolo Gentiloni, Johnson was asked if Britain should back calls from banks for a transitional arrangement to safeguard the City given that the EU separation negotiations were expect to be lengthy.

"I think that there is every reason to be optimistic about these talks," said Johnson, who campaigned for Brexit.

"London's financial services sector is a massive asset for the whole of the EU. It's a great benefit to the Italian economy as well as the UK economy," he said.

"I don't think anybody would want to see any detriment to that industry (London's financial services) here in Italy any more than we in Britain."

Johnson noted that Britons drank about 300 million litres a year of Italian prosecco wine.

"No one would want to see any tariffs on prosecco from Italy. We are the biggest drinkers of Italian wine in Europe. No one would want to see any tariffs on Italian wine any more, I think, than the Italian government would want to see any detriment to the interests of the City of London (LSE: CIN.L - news) ," he said.

Britons voted in a June referendum to leave the EU but new Prime Minister Theresa May has said she will not start the formal withdrawal proceedings this year.

May's aides suggest her plan is to invoke Article 50 of the EU's Lisbon Treaty, which triggers the exit process, early in 2017.

(Reporting by Philip Pullella; editing by Andrew Roche)