US President Donald Trump has said he strongly disagreed with Georgia state's aggressive push to reopen its economy in the midst of the novel coronavirus pandemic, saying it was "just too soon" to lift restrictions.

Georgia Governor Brian Kemp, a Republican and Trump ally, is allowing businesses such as beauty salons, tattoo parlours and bowling alleys to reopen as soon as Friday. Trump said Georgia is not adhering to federal guidelines for states to restart their economies.

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"It's just too soon. I think it's too soon," Trump said on Wednesday. "They can wait a little bit longer, just a little bit - not much. Because safety has to predominate. We have to have that."

Georgia has had more than 20,000 cases of COVID-19 and has seen more than 800 deaths.

But Trump at his daily briefing on the pandemic largely projected optimism in the nation's battle against the virus. He said he was encouraged to see other states begin to open up their economies and ease restrictions.

Trump's top adviser on the pandemic, Dr Anthony Fauci, said mitigation strategies were working, setting the stage for some states to reopen. He urged Kemp to proceed with caution.

"If I were advising the governor, I would tell him, be careful. I would tell him not to just turn the switch on and go," Fauci said, adding that Georgia could see a rebound of the virus, further damaging the state's economy.

In response, Kemp on Twitter praised Trump's leadership but said the state would move forward as planned.

"Our next measured step is driven by data and guided by state public health officials. We will continue with this approach to protect the lives - and livelihoods - of all Georgians," he said.

Given the favorable data trends, enhanced testing through @AUG_University, & advice of state healthcare leaders, we are taking another measured step forward. We remain focused on protecting lives - and livelihoods - in every part of Georgia. https://t.co/tWih2eRCcl #gapol — Brian Kemp (@BrianKempGA) April 21, 2020

Trump's reopening guidelines recommend 14 days of declining new infections before moving to the reopening phase that Kemp has called for. That means testing healthcare workers and people who show any symptoms, as well as the screening of asymptomatic people.

The number of tests administered in Georgia had plateaued between 3,500 to 4,000 a day. However, on Wednesday, the state reported almost 6,000 tests over 24 hours, with Kemp saying on a conference call with Republican US Senator Kelly Loeffler that Georgia was "really ramping up" its capacity.

However, despite these measures, many businesses and workers are holding back for fear of illness.

Dewond Brown, 42, was laid off in March from an Atlanta-area restaurant as a line cook, making him worried about his high blood pressure. He told The Associated Press news agency he would not go back if his employer reopened.

"I understand everybody wants to get back to normal, but you hear the medical people say everyday it's not time yet."