Dr Anthony Fauci from the US National Institute of Allergy and Infectious Diseases has said that the country’s testing system for coronavirus is not working.
Dr Fauci said: "The system is not really geared to what we need right now...let's admit it.”
His words come as US authorities face widespread criticism for carrying out fewer numbers of tests than other nations with confirmed cases.
In the UK, over 29,700 people had been tested as of March 12, with over 1,000 tests carried out per day.
Addressing Congress, Dr Fauci said that the US was "not set up" for widespread testing.
He said: "The idea of anybody getting it [testing] easily, the way people in other countries are doing it, we're not set up for that. I think it should be, but we're not."
President Donald Trump was defensive of test routines, saying that the US has a "a tremendous testing set up where people coming in have to be tested”.
Back in January, the White House declined the opportunity to use a World Health Organization approved coronavirus test, after the Centers for Disease Control and Prevention [CDC] had developed their own.
It has since emerged that with the initial CDC developed tests, there were faults, and many of the results came back inconclusive.
Vice-president Mike Pence told news outlet CNN on Thursday that he could not confirm how many US citizens had been tested, saying that he would “leave that to the experts”.
The CDC reported that as of March 12, 11,079 samples had been tested in the US since January. However, as individuals typically submit two samples, the actual number of individuals to have been tested is thought to be lower.