The Bank of England warned again Thursday that Britain's EU membership referendum next week was the "largest risk" facing financial markets, even as it held its interest rate at 0.50 percent.

"The outcome of the referendum continues to be the largest immediate risk facing UK financial markets, and possibly also global financial markets," read minutes from the BoE's June meeting, adding that "were the UK to vote to leave the EU, sterling's exchange rate would fall further, perhaps sharply".