Sterling slips after poll gives Brexit camp 1-point lead

(Updates after Opinium poll, recasts)

By Jemima Kelly

LONDON, June 22 (Reuters) - Sterling slipped on Wednesday after an opinion poll gave the "Leave" campaign a one-point lead over those who want to keep Britain in the European Union, less than 15 hours before voting in a membership referendum begins.

The Opinium survey of around 3,000 people, conducted between June 20 and 22, put support for "Leave" at 45 percent and "Remain" at 44 percent. Opinium's previous poll, published on Saturday and based on polling between June 14 and 17, had put the two camps level at 44 percent.

Sterling fell to as low as $1.4663 after Wednesday's poll, down from around $1.4712 before its release, then inched up to $1.4678 by 1600 GMT. That left it up 0.2 percent on the day but around 1 cent lower than the day's high of $1.4775.

Many investors reckon sterling could fall sharply in the event of a Brexit vote. Britain's large current account deficit - 7 percent of output in the last quarter of 2015 - makes the economy particularly vulnerable to any pull-back in investment flows.

The head of sterling portfolios at PIMCO, the world's biggest bond fund manager, said on Wednesday that sterling could fall to its lowest level against the dollar in 30 years if Britain votes to leave.

George Soros, the billionaire who earned fame by betting against the pound in 1992, said on Tuesday that Brexit would trigger a bigger and more disruptive sterling devaluation than the fall on Black Wednesday 24 years ago.

But not everyone agrees on the extent of the pound's vulnerability. BNY Mellon currency strategist Neil Mellor said that because sterling was already trading close to 30-year lows, it was difficult to see it falling precipitously if Britain voted to leave.

"Every time that sterling has fallen dramatically, whether that be in 1992 or 2008, it's come from a position of strength," he said. "A lot of long-term investors will look at the levels it's at against the dollar in particular and think there's a buying opportunity."

Mellor suggested that reticence to sell sterling at these levels had underpinned the currency after the Opinium poll, though added that so soon before the vote the market had become rather illiquid.

"I think everyone's made their bets." he said.

TOO CLOSE TO CALL

A telephone poll released on Tuesday by Survation for spread-betting firm IG (LSE: IGG.L - news) put support for "In" at 45 percent, just one percentage point ahead of "Out" on 44 percent.

Yet despite the polls continuing to suggest the outcome of the ballot is too close to call, online betting exchange Betfair said the implied probability of a vote to remain in the EU was around 75 percent.

That was a similar level to the chances given by Betfair on Tuesday, and was up from around 60 percent last Thursday, before the murder of pro-EU lawmaker Jo Cox that some have said contributed to a shift in sentiment towards the "Remain" camp.

Against the euro, the pound weakened to 76.85 pence after the poll, from around 76.70 pence before, leaving it down 0.1 percent on the day.

"Price action isn't overly aggressive at present, however volatility and uncertainty are omnipresent and will only get more severe," said Tobias Davis, head of corporate treasury sales at Western Union.

"No one will want to get caught on the wrong side of this, so position squaring will continue to dominate trade and liquidity will slowly dry up."

The cost of hedging against sharp swings in sterling/dollar over the next week, derived from an option that covers the vote and its results, hit a record high on Friday.

(Additional reporting by Anirban Nag; editing by John Stonestreet)