The prolonged uncertainty surrounding the outcome of UK Prime Minister David Cameron's EU renegotiation strategy is fuelling concerns among top UK business leaders, a new report has revealed.
Compared to similar polling from summer 2015, business backing for continued EU membership fell from 74 per cent to 62 per cent.
The report, by accounting giants Deloitte, polled around 137 chief financial officers (CFOs) from some of the UK's top FTSE 350 companies.
Using the same questioning as last summer, on whether CFOs believed that it is in the interests of British businesses for the UK to remain in the EU, slightly less than a third said their decision would depend on the outcome of David Cameron's renegotiation of UK membership.
The chief executive of Deloitte UK, David Sproul, said the findings showed that; "A clear majority of CFOs continues to favour the UK remaining in the EU, but the proportion of those expressing unqualified support has fallen."
Sproul added; "This mirrors what we have seen from the broader public in opinion polls in the last six months. With around one third of CFOs undecided on their position or awaiting the outcome of renegotiation discussions, the eventual deal may well significantly affect business attitudes to EU membership."
The accountancy giant's chief economist, Ian Stewart, suggested that the fall in corporate support showed that, "risk appetite has fallen to a three and a half year low, mirroring the loss aversion and caution being seen in financial markets."
"With a much sharper focus on cost control and less emphasis on growth through acquisitions and capital spending, CFOs' strategies are more defensive than at any time in the past three years."
"CFOs are most positive about growth in the UK and US in 2016. However, despite stronger than expected growth in the euro area in 2015, UK CFOs remain pessimistic about prospects for the region. Levels of confidence on growth in the euro area are lower than for emerging market economies," he added.
Robert Oulds, the director of Eurosceptic think-tank the Bruges Group, told the BBC that the drop in British corporate support for continued EU membership highlighted that; "Business leaders are beginning to think outside of the box and recognise that we do not have to be part of an EU political union to enjoy mutually beneficial trade links.
"If this trend continues then businesses will be firmly in favour of 'Brexit'," he added.
Meanwhile, David Cameron is expected to confirm rumours that ministers in his government will be allowed to campaign in favour of Brexit.
According to sources close to the UK Prime Minister, he will today (Jan 5) give, "a strong signal" that collective responsibility will be suspended during the in-out referendum campaign. This opens up the possibility of UK government ministers campaigning on opposing sides of continuing EU membership.