By Agnieszka Flak and Ben Hirschler

MILAN/LONDON (Reuters) - Milan's new mayor Giuseppe Sala will fly into London on Wednesday, stepping up a battle between European cities competing to wrest two prestigious European Union agencies from London in the wake of Britain's vote to leave the bloc.

The European Medicines Agency (EMA) and the European Banking Authority (EBA) together employ more than 1,000 skilled staff from across the EU. Both are expected to relocate as a result of the so-called Brexit decision.

The agencies are prized not only for jobs but also for their potential to act as hubs for finance and pharmaceuticals, two of Europe's most important industries.

That has set off a battle from Madrid to Stockholm to Warsaw as EU members seek to grab one or other organization, in the knowledge that banks and drugmakers will want to maintain close ties with key regulators.

Sala will meet the heads of the EBA and EMA during his one-day trip, which was arranged by the Italian ambassador in London, the mayor's office said.

Both bodies have Italians in top positions, with former Bank of Italy regulator Andrea Enria chairing the EBA and a one-time head of the Italian Medicines Agency, Guido Rasi, the executive director of the EMA.

They also have a lot of Italians working for them in London.

Sala's sales pitch for Milan includes the city's attractive lifestyle and convenient location, as well as the former Expo trade fair area he believes would make an ideal location for the EU bodies.

Still, the decision on the future location of the EBA and EMA will ultimately come down to horse-trading between European politicians and other cities are also keen.

The EBA, which employs 160 staff, has already said it will have to move and an EU official said last week it would likely relocate to either Paris or Frankfurt.

Its departure from Britain highlights how London's financial district can expect to be frozen out of EU financial regulation, and possibly from Europe's capital markets, depending on the terms of Brexit.

Governments in Italy and Spain base their case in part on the belief that they do not have their fair share of big EU organizations, while Poland argues it is time to recognize the importance of central European nations outside the euro zone.

Spain's Deputy Prime Minister Soraya Saenz de Santamaria last week announced the establishment of a working group to bid for the EBA and EMA.

Others lobbying in the wings for the EBA include Amsterdam, Luxembourg, Dublin and Vienna, while Stockholm and Copenhagen are both keen to house the EMA.

The EMA, which employs 890 people including temporary staff, says it is still awaiting guidance from Brussels on its future. But many pharmaceutical executives believe it will have to move once Britain invokes Article 50, the EU treaty clause triggering exit negotiations.

The big concern for the drugs industry is that a move from London could disrupt the work of the agency, which has acted as a one-stop-shop for drug approvals for two decades and also relies heavily on input from British experts.

"A rushed move will be very disruptive. We need to ensure the integrity of the regulatory system," Richard Bergstrom, director general of the European Federation of the Pharmaceutical Industries and Associations, told Reuters.

(Editing by Mark Potter)