Australian business leaders have offered their support to the 'Remain' campaign, warning that a Brexit would generate financial instability in global markets.

As Britons head to the polls on Thursday (23 June) for a historic vote which will shape the UK's future in the European Union, David McCredie, the chief executive of the Australian British Chamber of Commerce, urged them to vote to remain in the union.

"There's a great deal of uncertainty and in the business environment," he said, adding 54% of the Chamber's members support the UK remaining in the EU.

"Businesses love certainty, markets love certainty, and that sort of instability [from a Brexit] would be damaging and possibly crippling to the UK economy."

The vote could also have huge implications for many businesses in Australia, as Britain is the second largest destination for Australian foreign investment.

The likes of Westfield, AMP and the Future Fund have major investments in UK assets, while a number of Australian companies are worried a Brexit could make it more difficult for them to trade in Europe.

"If there's a challenge to the connectivity between the UK and the continent and Ireland of course then it may challenge that perspective for Australian investors looking at Europe," McCredie added.

Meanwhile, the latest poll, conducted online by Populus across 4,700 voters on 21 June and 22 June, has put the Remain side ahead by 55% to 45%. An earlier poll carried out by Ipsos Mori for the Evening Standard put the pro-European campaign in the lead 52% to 48%.