* Euro, GBP belted after central banks surprise with guidance
* Leaves Fed alone with tapering plans, to benefit of USD
* Dollar index within reach of 3-year high
* Markets turn their attention to US payrolls due later Friday
SYDNEY/TOKYO, July 5 (Reuters) - The dollar was broadly higher on Friday after Europe's two biggest central banks blindsided markets with decidedly dovish policy guidance, as attention turned to a crucial U.S. jobs report that could either bolster or weaken the case for an imminent reduction of the Federal Reserve's stimulus.
The dollar could extend its gains, possibly to test its near three-year high against a basket of currencies hit in May, if the upcoming U.S. employment figures show improvements in line with the Fed's forecast.
"At the moment, I see few reasons to sell the dollar given relative strength in the U.S. economy. Even if today's numbers are weak, that is unlikely to lead to a long downtrend in the dollar," said a trader at a Japanese trading house.
The dollar index made a swift turnaround, climbing from to as high as 83.906 , the highest since late May, having risen 4.2 percent from its low hit in June.
The index is within reach of its May 23 peak of 84.498, a break of which could add fresh momentum to the currency.
The euro fetched $1.2903, down 0.15 percent on the day after having fallen 0.9 percent on Thursday to hit a five-week low of $1.2883 at one stage.
The British pound hit a fresh five-week low of $1.5026 in Asia on Friday, stripped of gains made earlier in the week and having sunken 1.3 percent on Thursday.
The first shock came when the BoE under new governor Mark Carney broke with tradition and issued a statement that the market's pricing of future rate rises was unwarranted.
ECB chief Mario Draghi followed up by ending the bank's taboo on forward guidance, saying low rates would remain for an extended period of time.
European stocks bounded higher while bond yields fell. The premium paid by US 10-year Treasury yields over German Bunds widened to its highest since April 2010.
"The general message is that the possibility of further monetary stimulus in the near term is very high," said Martin McMahon, European economist for the Commonwealth Bank of Australia.
"That easing would probably come in the form of a refi rate cut to 0.25 percent, with a realistic prospect of a negative deposit rate," he added. "Further action at the August 1st ECB meeting may be a little early. But there is a strong chance of another rate cut after the summer break."
All of which is in stark contrast to the Fed, which plans to start tapering its stimulus before year-end should the U.S. economic recovery proceed as hoped.
The possible timing of that tapering will, however, depend on the flow of data and there are few more important than the payrolls report due later on Friday.
Forecasts favour a rise of 165,000 in employment, with the jobless rate ticking down to 7.5 percent from 7.6 percent in May, edging closer to "the vicinity of 7 percent", which Fed Chairman Ben Bernanke has signalled as a level to stop bond buying.
However, dealers are well aware that the series has a tendency to disappoint in June. Over the past sixteen years the report has come in under expectations 75 percent of the time with an average miss of 70,000. In addition, four of the last five June releases have fallen short of forecasts.
The U.S. dollar also gained 0.2 percent to 100.28 yen , ticking up near Wednesday's one-month high of 100.86.
Still, despite the latest firmness in the dollar, the option market is showing strong demand for dollar/yen puts, with risk reversal spreads still near the widest level in favour of dollar puts in two weeks.
"This is likely a result of speculators unwinding their bets against the yen," said Osamu Takashima, chief FX strategist at Citigroup Global Markets Japan.
"That seems to suggest that, if you look at two to three week terms, speculators will have fresh capacity to sell the yen," he said, adding that Japan's upper house election on July 21 could be a trigger for yen-selling.
Prime Minister Shinzo Abe and his coalition partner are expected to score a hefty victory, likely ending years of a hung parliament in Japan.