A poll published in The Guardian has shown a surprise swing towards British voters' support to leave the EU
Brexit would have a "substantial" impact on the global economy triggering turmoil in the world stock markets, the OECD has warned.
In its latest outlook forecast, the Organisation for Economic Co-operation and Development says fears over a potential Brexit have already knocked growth in the UK economy.
With just 23 days until the referendum, the think-tank is ramping up its warnings about the risks of leaving the EU, saying that if the UK voted to leave, there would be a "significant impact" on Europe and the rest of the world.
It said: "A decision to exit would result in considerable additional volatility in financial markets and an extended period of uncertainty about future policy developments, with substantial negative consequences for the United Kingdom, the European Union and the rest of the world."
The OECD caution echoes the warning from other major economic forecasters, including the Bank of England, the Institute for Fiscal Studies and the International Monetary Fund.
The 'Vote Leave' campaign has criticised the forecasters for being biased.
Meanwhile, sterling values dropped yesterday after a poll published in The Guardian showed a surprise swing towards support to leave the EU.
A poll carried out over the phone and online found that 52% of voters support an exit - giving it a 4% lead over the 'remain' side.
When the newspaper carried out a corresponding poll in mid-May the 'remain' side had a 10 percentage point lead.
The pound sterling dropped by almost 1% to 76.79p per euro.