The United States accounts for nearly a third of the 2.25 million coronavirus infections reported globally. It has also recorded over 37,000 deaths, more than any other nation, followed by Italy, Spain and France.

Meanwhile, demonstrators in three US states staged rallies this week to demand an end to the restrictions, with the largest protest in Michigan attracting 3,000 people — some of whom were armed.

Trump has largely left decisions on easing lockdowns to state officials even as he laid out guidelines for a staged reopening of the national economy.

But his call to "liberate" Michigan, Minnesota and Virginia in a series of tweets Friday were rebuked by the Democratic leaders of all three states.

"I do not have time to involve myself in Twitter wars," said Virginia governor Ralph Northam.