The US economy showed less-than-stellar growth in final weeks of 2019, but produced solid Christmas sales and enters 2020 with a "modestly favourable" outlook, the Federal Reserve has said. 

On the day the US and China signed a long awaited partial trade truce after months of conflict, the Fed said tariffs continued to weigh on the economy in some regions. 

The Fed's "beige book" survey of conditions nationwide painted a mixed picture, with circumstances improving in the Richmond and Dallas regions but lacklustre in the Philadelphia, St Louis and Kansas City regions.  

"In many districts, tariffs and trade uncertainty continued to weigh on some businesses," the report said.

But it added that "expectations for the near-term outlook remained modestly favorable across the nation."

US President Donald Trump last month relieved some of the pressure on American businesses by canceling a planned round of tariffs on Chinese goods, and slashing some others as part of a partial trade deal with Beijing, ending nearly two years of escalating conflict. 

The two sides signed the deal yesterday. 

But many of the China tariffs remain in place - costs borne by US businesses and consumers, which are weighing on investment and growth - and Trump also has slapped tariffs on European exports including wine, and threatened to do more. 

In the Philadelphia region, the looming wine tariffs "prompted an area merchant to stock up with over 35,000 cases" to beat the sanctions and minimise price hikes, according to the report.

Overall economic growth in the area "slowed to a slight pace," it said. 

Across the US, "holiday sales were said to be sold" in the crucial annual shopping period, while tourism was "mixed" and manufacturing - a sector hit badly by Trump's trade wars - was "essentially flat" in most areas.

Labour remained scarce, with employers struggling to fill open positions, a trend that now dates back more than a year. 

But in the manufacturing, transportation and energy sectors, there were job cuts and reduced hiring. 

Fed policymakers cut interest rates three times in 2019 but said toward the end of the year they did not expect to do so again unless circumstances changed substantially. 

The beige book report was prepared in advance of the Fed's next policy meeting January 28-29 

Markets overwhelmingly expect policymakers to leave interest rates untouched until November at the earliest.