By Huw Jones

LONDON (Reuters) - Europe's biggest stock exchange Bats Europe could open a base outside London following Brexit, its head told Reuters, voicing doubts about whether the City of London would secure sufficient access to the European market.

Bats Europe accounts for about 24 percent of daily trading in European shares and a shift of UK operations of one of the financial sector's biggest success stories would be a blow to London's prestige as a global financial center.

Barring a clear sign that Britain will get full access to the single European market, Bats will begin work on setting up a second base next year if Brexit is expected in 2019, Bats Europe Chief Executive Mark Hemsley said.

He said while no firm decision had been made on whether to relocate some operations to the European Union if Britain leaves the bloc, there was no real alternative as things stand.

"If I look at the current scenarios, the only one that does give certainty to your customers is to actually have an entity within an EU country," Hemsley told Reuters, citing Dublin in Ireland as a possible location.

"Until we see a path that tells us otherwise, that will be the most likely outcome at the moment."

Britain voted to leave the European Union in a June referendum although the government has yet to trigger the official departure process, which is referred to as Brexit.

Uncertainty about what kind of trade deals Britain will be able to negotiate with Brussels is forcing many companies with pan-European businesses to come up with contingency plans.

The comments by Bats Europe's CEO are the latest sign firms are wary about waiting too long for fear of losing customers.

Financial firms based in London use a so-called EU passport to offer services across the bloc from one base, but few expect to have continued full access to Europe's single market after Brexit.

While Britain will negotiate new trade terms with the EU Hemsley said all the scenarios aired so far - being part of European Economic Area like Norway, bilateral deals like Switzerland and Canada, "equivalence regimes", or relying on World Trade Organization rules - were problematic.

British Prime Minister Theresa May has talked of a "bespoke" deal with Europe but so far there have been no details and much hinges on what terms EU member states will accept.

Bats Europe was created in 2011 when U.S. Bats snapped up Chi-X Europe, then a four-year old trading platform that had became one of Europe's biggest exchanges, eclipsing national exchanges that are centuries old in some cases.


Hemsley said he was open-minded about which country Bats would chose but said the Irish capital was attractive.

"We are looking at the underlying legal framework of a country and Ireland is quite attractive because it's the most similar to the UK structure," Hemsley said.

"We look at local tax environments, labor laws, availability of personnel. We are open minded, but Dublin is attractive on a number of those levels."

Consultants and lawyers have warned of a logjam as London-based banks and financial firms queue at the doors of regulators in other EU countries to obtain a financial services passport.

Bats only obtained its full passport as an exchange in 2013 from Britain's Financial Conduct Authority and Hemsley said an awful lot of the documentation needed for a new passport was already at hand.

"Whilst there are going to be quite a lot of banks moving, when you come to moving exchanges, there are probably not going to be an awful lot of them," Hemsley said, adding that a second base in the EU would have "some regulatory and legal presence".

"I still think London is going to be a substantial trading hub even if there is more fragmentation of trading across Europe because of Brexit," Hemsley said. "From a physical point of view we would still have substantial operations in London."

(Editing by David Clarke)