US Vice President Joe Biden has unveiled sweeping new Covid-19 regulations requiring workers at major corporations to get vaccinated or face weekly testing.

The measures, which include a vaccination mandate for millions of federal government employees, come as the president faces an increased pressure to battle a surge in cases.

Covid-19 has killed almost 650,000 Americans, and hospitals are at capacity.

He had promised a "summer of freedom" from the virus, but the Delta strain has seen an increase in cases.

In a speech at the White House on Thursday,  Biden instructed the US Department of Labor to compel all private firms with 100 or more employees to demand the jab or request confirmation of a negative coronavirus test from employees at least once a week.

The directive will affect around 80 million workers.

"This is not about freedom or personal choice, it's about protecting yourself and those around you," Biden said while unveiling the mandate.

Most of the adult American population has got jabbed by at least one dose of coronavirus.