Total US coronavirus cases surpassed 2 million on Wednesday, according to a Reuters tally, as health officials urge anyone who took part in massive protests for racial justice to get tested.

Nationally, new infections are rising slightly after five weeks of declines, according to a Reuters analysis.

Part of the increase is due to more testing, which hit a record high on June 5 of 545 690 tests in a single day but has since fallen, according to the COVID-Tracking Project.

Recent increases in cases are likely a result of more people moving about and resuming some business and pleasure activities as all 50 states gradually reopen.

Health officials believe the first US coronavirus cases appeared in January, and the nation recorded 1 million cases by April 28.

So far in June, there have been an average of 21 000 new cases a day compared with an average of 30 000 a day in April and 23 000 a day in May, according to a Reuters tally.

Total US coronavirus-related deaths have surpassed 112 000, also the most in the world.

On May 12, the World Health Organisation (WHO) advised governments that before reopening, the rate of people testing positive for the coronavirus should remain at 5% or lower for at least 14 days.

US rates of positive test results have fluctuated between 4% and 7% nationally and have not met those guidelines, although many individual states have.

Some states were still reporting positive rates above the WHO threshold last week, with Maryland at 8%, Utah at 9%, Nebraska at 9%, Virginia at 9%, Massachusetts at 11% and Arizona at 12%.

At the peak of the outbreak in April, 25% to 50% of tests came back positive.