Slaughter and May is planning to relocate six competition lawyers from London to Brussels this year, amid a spike in work prompted by last year's Brexit vote.

The magic circle firm's latest partner promotions, announced last week, included City competition lawyer Kerry O'Connell, who will move from London to Brussels before the end of the year.

O'Connell, who has already spent a significant part of her career building her practice in Brussels, will be followed to the Belgian capital by five City competition associates, as the firm ramps up its response to the Brexit vote.

"Brexit has created many challenges – it is a critical time. We have to invest and make sure we provide an international product to our clients," said London-based competition head Philippe Chappatte. "We have been developing a 'triple hub' strategy for a number of years. What Brexit has done is accelerate our plan to move lawyers to Brussels.

"The plan was always to carry on building our Brussels office. We think it is already a premier tier one operation; it punches way above its weight and we will carry on building it up as well as Hong Kong/Beijing and London."

Slaughters currently has three partners based in Brussels. In total, the firm is aiming to have 20 lawyers on the ground by the end of 2017.

Brexit has created many challenges – we have to invest and make sure we provide an international product to our clients

O'Connell's promotion this May will take the firm's global competition partner headcount to 11, almost double the six the practice had five years ago. In total, Slaughters now has more than 75 competition lawyers, after the addition of around 15 associates per year in recent years.

Chappatte, who took over leadership of the practice in 2009 and was re-elected in 2011, commented: "What will change over the coming years is that we will have more partners based in Brussels for their entire careers, rather than rotating out of London."

Chappatte explains that when the UK officially exits the EU, major merger filings will not just be done at the European level but also with the UK authorities.

"The rationale for building Brussels is to ensure that our footprint in Brussels is large enough to handle large cases out of Brussels," he said. "Some clients will want EU merger cases handled out of the Brussels office post-2019. We will achieve this not only through having four partners in Brussels and the requisite number of associates, but also by ensuring that [London competition partners] Bertrand Louveaux, Claire Jeffs and I, who have substantial EU competition practices, maintain our profile in Brussels post-Brexit."

Slaughters is also looking to capitalise on Brexit's implications by boosting its trade capabilities. "We are increasing our knowledge of what trade agreements involve," said Chappatte. "It is not an area many magic circle law firms know much about – we are looking at opportunities to develop here."

In future, Chappatte suggests that the Brussels practice will be "more European and less British". The firm's three partners there are Belgian, Finnish and Irish, while incoming partner O'Connell has applied for Irish nationality.

Last year, Legal Week reported that Slaughters lawyers, alongside others from top UK firms, were applying to join the roll of solicitors in the Republic of Ireland ahead of the Brexit vote.

Chappatte comments: "All lawyers in our group have had the opportunity to register in Ireland, but nobody needs an Irish practicing certificate today; it is costly and unnecessary. Over time, our Brussels practice will become more and more European and less and less British."