Financial markets were plunged into turmoil today as the latest Brexit opinion polls sent investors running for the hills, wiping tens of billions off the value of the UK's leading companies.

The FTSE 100 shed two per cent to end the day at 5,923.53 – its lowest close since 24 February – knocking roughly £30bn from the value of London-listed firms, as yet more opinion polls showed the Brexit camp stretching its lead in the EU referendum campaign.

From there, it was one-way traffic all across Europe. Market commentators were not unjustified in their metaphor-heavy analysis of the day's performance.

"Brexit is adding fuel to the fire for risk averse investors," said Jasper Lawler at CMC markets.

“Panic appears to be gripping markets as the headlines fill up with references to a possible Brexit … The phrase ‘sea of red’ has never seemed more appropriate," added Chris Beauchamp senior analyst at IG.

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No sector was safe from the sell-off with miners Anglo American and Antofagasta – the worst performers losing more than five per cent – followed by the likes of Sky, BHP Billiton, Morrison's and Taylor Wimpey.

Sterling was also down one per cent against the dollar at $1.4140.

Across the Channel, the Eurostoxx 50 was off by two per cent, the Cac 40 in France tumbled by 2.3 per cent, while the Dax lost 1.4 per cent in Germany.

Read more: Muted demand for extra sterling in Bank of England special auction

In the dash for safe assets, yields on government borrowing costs tumbled as demand for sovereign-backed debt boomed. The 10-year UK bond shed more than 0.08 percentage points – or basis points – to 1.12 per cent, its lowest on record. German 10-year debt also turned negative, hitting minus 0.03 per cent before recovering slightly to minus 0.01 per cent.

It was also revealed that the European Central Bank (ECB) is preparing to hold emergency conference calls and issue "whatever it takes" statements on the morning of 24 June – when the referendum result will be announced – in order to try to limit the contagion in the financial markets.