* Dollar hit after some polls show Trump leading Clinton
* Swiss franc, yen surge as investors seek safe havens
* Euro hits three-week high close to $1.11
* Mexican peso at weakest in a month vs dollar
* Fed awaited, but politics seen overshadowing fundamentals (Updates after start of European trade)
By Patrick Graham
LONDON, Nov 2 (Reuters) - The dollar slumped and the Swiss franc and Japanese yen surged on Wednesday as investors worried by the prospect of a Donald Trump presidency sought out safe havens for their money.
The yen, driven lower in the past month as investors abandoned long-term bets on it strengthening past 100 yen per dollar, gained more than half a percent to hit its highest since Oct. 21 against the dollar.
The franc hit its highest in a month against the greenback and a four-month peak against the euro. It has gained almost 3 percent in the past week as improving polls for Trump prompted investors to trim bets on a rise in U.S. interest rates in December.
Polls on Tuesday put Trump ahead by 1-2 percentage points, although Clinton held a five-percentage-point in a Reuters/Ipsos opinion poll released on Monday.
"The resurgence of Donald Trump in the polls so close to election day has seriously rattled investors," said Craig Erlam, senior market analyst with Oanda in London.
"It's been clear for some time now that markets would much prefer the stability that a Clinton victory would bring for the U.S. economy and the reaction over the last 24 hours or so since the polls started to change so dramatically just confirms this."
The euro, whose extremely low interest rates have increasingly seen it gain at times when investors are feeling less sure about global economic growth, gained a third of a percent to hit a three-week high of $1.1099.
While some argue that a Trump presidency might lead to substantial repatriation of funds to the United States - and hence into dollars - the running assumption of markets in the past month has been that the dollar would fall if he won.
That largely seems the product of the potential for investors to take risk off the table, as they were on Wednesday, as well as the prospect that any blip on markets globally might cause the U.S. Federal Reserve to put a rise in interest rates on hold.
As Clinton moved ahead after Trump was linked to sex scandals last month, investors bought the dollar and priced in a strong chance of a Fed move in December.
The Fed ends its two-day November meeting on Wednesday and will issue a statement that is widely expected to open the door, on economic grounds, to a rise next month.
"Neither a positive signal sent out by the labour market report (on Friday) nor the willingness of the Fed to hike rates is likely to constitute a reason for the market to trade the dollar stronger today," said Commerzbank (DE:CBKG) strategist Esther Reichelt.
"The market knows full well that everything could look very different in a week's time."
(editing by John Stonestreet)