UNITED NATIONS -- UN Chief Economist Elliott Harris said Thursday that the signing of the phase-one economic and trade agreement between China and the United States is a positive sign and helps reduce some of the uncertainties.

"Progress in achieving agreement to resolve some of the simmering trade disputes is a positive sign, and it will reduce some of the uncertainties that have been plaguing investment, and will certainly lead to a resuscitation of some of the trade flows," said Harris at a press conference launching the UN World Economic Situation and Prospects (WESP) 2020 at the UN headquarters in New York.

"And we hope that it is strong enough to counter some of the decline and weaknesses we've seen in the global economy over the last couple of years," said the Harris, who is also UN assistant secretary-general for economic development.

Calling the agreement part of the progress relative to the current situation, Harris, however, cautioned "not to assume that that has resolved all of the problems."

"We would caution against thinking that this is a positive development in all respects," he said.

China and the United States formally signed their phase-one economic and trade agreement in Washington on Wednesday, with Chinese Vice Premier Liu He and US President Donald Trump inking the papers in the White House.

The latest UN WESP expected a global growth of 2.5 percent in 2020, but meanwhile warned of a flare-up of trade tensions, financial turmoil, or an escalation of geopolitical tensions, which would derail a recovery.