The progress of US economic recovery has been thrown into doubt after new figures showing the weakest pace of monthly employment growth in three years.
Just 74,000 jobs were added in December as questions were raised about whether strong gains over previous months could be sustained.
The data left the picture for 2013 ending on a weak note and sowed confusion among analysts who said other indicators suggested the world's largest economy had been picking up steam.
It may also have left central bankers at the US Federal Reserve in a quandary over how to proceed with the scaling back of quantitative easing (QE), which is injecting billions into the economy each month - a "tapering" which began in December.
The developments have significance globally because of America's importance as a trading and investment partner with the rest of the world.
December's paltry gain in jobs was well below the average 214,000 seen in the preceding four months but some analysts noted the positive impact of an upward revision of November's figure by 38,000 to 241,000.
It was also noted that the slowdown might have been a result of the poor weather in the final month of the year slowing hiring.
The unemployment rate itself fell sharply from 7% to 6.7%, the lowest level for more than five years, but this was largely attributed to more Americans no longer even looking for jobs and therefore not counted in the calculation.
Dan Greenhaus, chief global strategist at brokerage firm BTIG, said: "We stop short of making larger observations base upon this number.
"The economy, based on any number of other indicators, has been picking up steam of late which makes today's number curious."
Rob Carnell of ING Bank said it would raise doubts about whether QE would be cut by a further 10 billion US dollars (£6 billion) a month in January after being pared back from 85 billion US dollars (£52 billion) to 75 billion US dollars (£45 billion) in December.
However, he said markets and the Fed would probably want to wait for confirmation of the initial figures "before throwing in the towel on the US recovery story".
The pound held its own against the dollar but was held back from gains by the UK's own disappointing figures from the construction and manufacturing sectors.
A shares rise in the FTSE 100 Index was untroubled by the developments, partly because weak US performance would be seen as more likely to mean continued low interest rates and QE support.