Some European firms could look to downsize their presence in the UK should the British public vote in favour of leaving the European Union (EU) in today's referendum.

Speaking to Legal Week, the leaders of leading independent firms Garrigues, Magnusson and Hengeler Mueller are bracing themselves for a potential Brexit and predicting a period of market volatility should it happen.

Dirk Bliesener (pictured), managing partner of Slaughter and May's German best friend, Hengeler, said it was possible some firms may look to downsize their presence in London if the UK left.

He said: "I think Brexit would be detrimental to business. The free market is the basis of transactions in capital markets and finance and I think this principle may be undermined if the UK leaves the EU."

"The question for us will be: does it make sense to be present in London? That's a question people will ask. Many teams working on continental transactions in London could be relocated to other places, so the benefit of having a presence there may change."

Bliesener spoke just before flying to Madrid for an aptly timed meeting of Slaughters' European 'Best Friends' network this evening. The meeting was planned over a year ago, so the timing is coincidental.

Fernando Vives, executive chairman of Spanish law firm Garrigues, said the firm would not downsize in London regardless of the outcome but believes Brexit would have a negative impact on deal activity.

"I think there would be a movement of currencies and a degree of volatility on the securities market, which will last for a certain amount of time, but no economic chaos."

He added: "We do not intend to reduce our presence in London, a city we see as key in terms of our cross-border deals."

Per Magnusson, senior partner of Swedish firm Magnusson, which does not have an office in the UK capital but has bases across continental and eastern Europe, suggests other legal markets could gain if the UK were the leave the EU.

"Other parts of Europe, the big legal markets of Germany, France and Spain, could see an opportunity to compete in a more aggressive way," he said. "The UK firms have such a dominant role in Europe, so maybe some European firms could see an opportunity here to actually do something."

He also said Brexit may "open up opportunities" for "more extensive cooperation" between firms outside the UK.