The pound surged in morning deals to USD 1.4947 -- its highest level since December 28 -- as Britons headed to the polls in a hotly-contested in-or-out EU membership vote. Results are due early Friday.
Sterling hit the pinnacle in frenetic foreign exchange activity as a new Ipsos MORI opinion poll put "Remain" on 52 per cent and "Leave" on 48 per cent.
The British currency also struck a three-week high point at 76.23 pence to the euro.
"The market is now fully expecting a win for the Remain camp," City Index research director Kathleen Brooks told AFP.
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"The sharp upswing towards $1.50 was also reflective of what was going on with the EU referendum odds.
"The market that looks at the margin of victory for the Remain camp started to price in a win for Remain by a fairly decent margin."
In afternoon London trade, the pound stood at $1.4790 as profit-taking set in. It also pulled back to stand at 76.69 pence to the euro.
Firstly, investors were unwinding their trading positions made in anticipation of a potential Brexit -- or British exit from the 28-nation bloc.
And secondly, a Remain outcome would curb the chances of an economic shock that might otherwise have prompted easier monetary policy from the Bank of England (BoE).
"Mounting expectations of victory for Remain prompted an unwinding of Brexit hedges, boosting the pound," Stamenkovic told AFP.
He added: "A vote for Remain would lessen the chances of a BoE easing, as uncertainty over the UK economy diminishes, lifting the pound.