South Korea's SolGent has secured an order to supply a US government agency with an additional 7,500 kits which can each perform 100 coronavirus tests, the CEO of the biotech firm told Reuters.
That will double the number of tests US authorities can perform using kits sourced from South Korea to 1.5 million.
SolGent has already sent kits for 150,000 tests while South Korean peers Osang HealthCare and SD BIOSENSOR are due to ship kits capable of performing 600,000 tests on Tuesday, company sources told Reuters.
The kits are being sent to the US Federal Emergency Management Agency (FEMA) after an appeal from US President Donald Trump.
Trump made a request for medical devices in a telephone call with South Korean President Moon Jae-in on March 25.
The US death toll from COVID-19, the lung disease caused by the virus, topped 23,600 on Monday, the highest of any country.
SolGent CEO You Jae-hyung told Reuters that the company is in talks on a long-term contract with FEMA and about building a factory in the United States to manufacture the testing kits, but that a decision has not been made.
US Ambassador to South Korea Harry Harris said on Twitter Tuesday that testing kits had been loaded at Incheon Airport bound for the United States.
He called the alliance between the two countries "ironclad" and thanked South Korea's foreign ministry for its help.
FEMA did not immediately respond to Reuters' emailed inquiries. The foreign ministry declined to comment.
The ministry had said that three companies had won preliminary approval from the US Food and Drug Administration (FDA) to export kits, but did not identify the firms.
After struggling with the first large outbreak of the virus outside of China, South Korea has largely managed to curb its spread without lockdown orders helped by a massive testing campaign and intensive contact tracing.