WASHINGTON (REUTERS) - New York City Mayor Bill de Blasio said on Monday (April 20) that it could take weeks if not months before the country's most populous city reopens due to a lack of widespread testing, even as officials elsewhere began rolling back restrictions on daily life.

Mr de Blasio, whose city is at the epicentre of the coronavirus crisis in the United States, said New York needed to be conducting hundreds of thousands of tests a day and to see hospitalisations decline further before reopening the economy.

"We could get there but we can't do it without widespread testing and so far the federal government still can't get their handle on that," Mr de Blasio said on MSNBC's "Morning Joe," adding that ending social distancing too soon could rekindle the virus.

"The federal government, especially, needs to get the memo that this thing ain't over and if you pretend it's over it is only going to boomerang back and make it worse."

Mr de Blasio's warning on testing echoed comments by several governors over the weekend disputing President Donald Trump's claims that they have enough tests for Covid-19, the respiratory disease caused by the novel coronavirus.

The United States has by far the world's largest number of confirmed coronavirus cases, with more than 750,000 infections and over 40,500 deaths, nearly half of them in the state of New York, according to a Reuters tally.

Mr Trump's guidelines to reopen the economy recommend a state record 14 days of declining case numbers before gradually lifting restrictions.

Yet the Republican president appeared to encourage protesters who want to reopen sooner with a series of Twitter posts on Friday calling for them to "LIBERATE" Michigan, Minnesota and Virginia, all run by Democratic governors.

An estimated 2,500 people rallied at the Washington state capitol in Olympia to protest Democratic Governor Jay Inslee's stay-at-home order, one of several protests.

Residents in Florida were allowed to return to some beaches after Governor Ron DeSantis approved the relaxing of some restrictions.

Mr Charlie Latham, mayor of Jacksonville Beach, said the first weekend the beach there was reopened with limited hours went well, with no arrests for people violating social distancing rules, which included a prohibition of chairs or blankets.

"We thought that the public was ready to maintain the social distancing standards and to exercise good judgment. And it's paid off, it's paid off really well," Mr Latham told Fox News.