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UPDATE 1-Sterling soars, helped by business surveys and weaker dollar

* Graphic: World FX rates in 2019 http://tmsnrt.rs/2egbfVh

* Graphic: Trade-weighted sterling since Brexit vote http://tmsnrt.rs/2hwV9Hv (Recasts, adds quotes, details, latest prices)

LONDON, Jan 6 (Reuters) - Sterling rebounded on Monday as investors who had sold the currency for safe havens after the United States assassinated an Iranian general returned to the pound.

Analysts said an upward revision to a business survey probably helped the pound, while the focus for investors now shifts to a parliamentary debate on Brexit legislation on Tuesday.

"We've got some better than expected PMIs, but some of it (the move higher in sterling) has been sentiment driven," said Morten Lund, an analyst at Nordea. "It's a bit surprising, but I think some of it is positioning."

The Purchasing Managers Index survey for Britain's services for December came in with a final reading of 50, better than the 49.1 reading forecast by economists polled by Reuters.

Optimism among companies has improved markedly since the election, although the economy continues to stagnate, the PMI survey showed.

Investors have remained cautious about the pound since Prime Minister Boris Johnson's Conservatives won the Dec. 12 general election. They worry about more political uncertainty as Britain prepares to leave the European Union and the two sides begin negotiations over their future trading relationship.

RBC Capital Markets currency strategist Adam Cole noted that "the provisional PMIs for January (out Jan 24) will be more interesting as they will shed some light on the potential for a rebound in activity early in 2020 as political uncertainty cleared following the election."

The UK parliament returns on Tuesday and will debate the Brexit bill, which includes a clause ruling out any extension of the transition period for trade talks beyond December 2020.

The pound rose 0.7% to as high as $1.3163 on Monday but remains below last week's $1.32.

Sterling fell on Friday after the U.S. assassinated the Iranian general Qassem Soleimani, panicking investors and boosting demand for safe-haven currencies, including the dollar.

The pound was also higher against the euro on Monday, rising 0.4% to 85.065 pence.

The British currency still remains some way off its more than three-year high of 82.78 pence per euro reached last month. (Reporting by Tommy Reggiori Wilkes, editing by Larry King)