A staff member (L) hands packages to a delivery man outside a chocolate store in Suffolk County of Long Island, New York state, the United States, May 27, 2020.(Xinhua/Wang Ying)

An economist called the rise of U.S. weekly jobless claims "one of the clearest signs yet that the U.S. recovery is stalling."

WASHINGTON, July 23  -- The number of initial jobless claims in the United States rose to 1.4 million last week amid a resurgence in COVID-19 cases, reversing nearly four months of consecutive declines in new applications, and raising uncertainty over the prospect of economic recovery.

In the week ending July 18, the number of Americans filing for unemployment benefits increased by 109,000 from a revised 1,307,000 in the prior week, the Labor Department reported Thursday.

"That marks the first increase since the end of March as re-imposed restrictions on businesses activity have taken a toll on employment," Sarah House, senior economist at Wells Fargo Securities, wrote in an analysis, calling it "one of the clearest signs yet that the U.S. recovery is stalling."

Several U.S. states, especially those in the South and West, have recently seen an uptick in COVID-19 cases, and over 20 states have already paused or partially reversed reopening efforts amid an alarming resurgence of cases.