With signs of a weakening economy spreading and financial markets gyrating, Fridays monthly jobs report will be watched for any evidence that the turmoil might be threatening the critically important US job market.

Economists have forecast that the government will report that employers added a modest 145,000 jobs in September and that the unemployment rate remained near a five-decade low of 3.7 per cent for a fourth straight month.

A job gain of that level would top August's increase of 130,000 and, if sustained, would likely be just enough to absorb new job seekers. But it would still be noticeably lower than last years average monthly job growth of 225,000.

With the US economic expansion in its 11th year and unemployment low, many businesses have struggled to find the workers they need. That is likely a key reason why hiring has slowed since last year.

But it is likely not the only reason.

The jobs figures will carry more weight than usual because worries about the health of the US economy are mounting.

Manufacturers have essentially fallen into recession as US businesses have cut spending on industrial machinery, computers and other factory goods. Overseas demand for US exports has fallen sharply as President Donald Trumps trade conflicts with China and Europe have triggered retaliatory tariffs.

A measure of factory activity fell in September to its lowest level in more than a decade. New orders for manufactured items slipped last month, the government reported.

Persistent uncertainties about the economy in the face of Trump's trade conflicts and a global economic slump are also affecting hotels, restaurants and other service industries. A trade groups measure of the service sector has hit its lowest point in three years.

The job market is the economy's main bulwark. As long as hiring is solid enough to keep the unemployment rate from rising, most Americans will likely remain confident enough to spend, offsetting other drags and propelling the economy forward.

But a slump in hiring or a rise in the unemployment rate in coming months could discourage consumers from spending as freely as they otherwise might during the holiday shopping season.

"We are at a very critical juncture," said Mark Zandi, chief economist at Moodys Analytics. "If we can stabilise job gains at about 125,000, the expansion will continue on."

Consumers are still mostly optimistic, and their spending has kept the economy afloat this year. But they may be growing more cautious. Consumer confidence dropped sharply in September, according to the Conference Board, a business research group, although it remains at a high level.

Americans also reined in their spending in August after several months of healthy gains. The 0.1pc increase in consumer spending that month was the weakest in six months.

Other parts of the US economy are still holding up well. Home sales, for example, have rebounded as mortgage rates have fallen, helped in part by the Federal Reserves two interest rate cuts this year. Sales of existing homes reached their highest level in nearly 18 months in August and new home sales soared.

Americans are also buying cars at a still-healthy pace. Consumers would typically be reluctant to make such major purchases if they were fearful of a downturn.

"As long as the consumer hangs in there, well be fine," said Ryan Sweet, an economist at Moodys Analytics.