British businesses will have to adapt to the "momentous turning point" brought upon by the European Union referendum, the Confederation of British Industry (CBI) said on Friday (24 June).

The Leave campaign won the referendum by 52% to 48%, prompting Prime Minister David Cameron to hand in his resignation – although he will only step down in October – sending shock-waves through the financial markets.

Shortly after the opening bell, London's FTSE 100 was down by almost 11%, with financial stocks and housebuilders bearing the brunt of the collapse, while the pound plunged to a 31-year low.

However, Carolyn Fairbairn, CBI director-general, stressed businesses will have to adapt to a new financial and political landscape.

"The British people's vote to leave the EU is a momentous turning point in our history," she said.

"The country has spoken and it's for us all to listen. Many businesses will be concerned and need time to assess the implications. But they are used to dealing with challenge and change and we should be confident they will adapt."

European Parliament President is 'very sad' about BrexitReuters

Calling upon "strong and calm leadership", she urged the Bank of England and Downing Street to take the required measures to ensure volatility is kept to a minimum in the short-term and to shore up confidence and stability in the economy.

Adam Marshall, the acting director general for the British Chamber of Commerce, also stressed the immediate priorities for UK business were market stability and political clarity.

"Some business people will be pleased with the result, and others resigned to it," he said.

"Yet all companies will expect swift, decisive, and co-ordinated action from the government and the Bank of England to stabilise markets if trading conditions or the availability of capital change dramatically."

He added firms across the UK were now likely to demand an immediate and unambiguous statement from the prime minister on the next steps, along with a clear timeline for the UK's exit from the European Union.

"Businesses will also want to see a detailed plan to support the economy during the coming transition period – as confidence, investment, hiring and growth would all be deeply affected by a prolonged period of uncertainty," he said.

Meanwhile, following news of David Cameron's resignation, the Federation of Small Businesses (FSB) urged the government to clarify what the vote will now mean for businesses, including how they will have access to the single market and the free movement of people and trade.

"These are crucial questions that need to be answered swiftly to ensure the confidence of the UK's 5.4m small businesses does not fall any further, as it is already at the lowest levels since 2013," said Mike Cherry, national chairman of the FSB.

"This includes clarity over the practical implications of this result on how smaller firms do business."