Companies seeking to "bulk up" to offset the uncertainty caused by Britain's looming EU exit helped to spur a near doubling of domestic mergers and acquisition activity this year, according to Thomson Reuters data.

The volume of UK domestic deals surged to €56.75 billion from €28.6 billion in 2016 as the number of deals between British groups jumped from 1,480 to 1,681, the highest level since 2008, the data show.

They included online gambling company GVC's purchase of bookmaker Ladbrokes Coral for as much as £3.9 billion and Hammerson's £3.4 billion pound acquisition of rival shopping centre operator Intu Properties.

It comes against a backdrop of often fractious Brexit negotiations between London and Brussels this year, talks that are yet to provide businesses with clarity about Britain's future relationship with Europe.

Bosses at British companies have also been eyeing new US President Donald Trump, whose decisions have repercussions for businesses around the world.

"At the beginning of 2017 there were a lot of questions about what was going to happen to the M&A market, given the global uncertainty caused by Brexit and the new U.S. president," said Nick Cline, a London-based M&A partner at law firm Latham & Watkins, who said the uncertain environment had acted as a driver for some deals rather than stifling activity.

"There are a lot of corporates out there in the UK and Europe who are seeing the changing landscape and as a result are even more focused on what they're going to do to be tomorrow's leaders."

The jump in domestic deal-making contrasted with falls in both inbound and outbound UK M&A volumes, the data show, with the former slipping 12.9% to €96 billion and the latter down 9.4% to €93.9 billion.

That meant overall M&A volumes with any UK involvement dipped 0.7% to €313 billion, a softer decline than the 1.4% slide in global deal volumes to €2.92 trillion, according to the data.