Sweden health authorities said on Tuesday that the test kit, which has been widely exported to other countries, could not distinguish between very low levels of the virus and a negative result.

BGI said devices sensitive enough to detect a smaller amount of the virus would deliver positive results, while less sensitive products would return negative results.

"The company's test has relatively high accuracy and received positive clinical assessment," it said.

The global surge in demand for coronavirus test kits has allowed BGI to expect its net profit to jump about eight times in the first half of this year.

But the purchase of test kits from BGI, which has grown into one of the world's largest genomics companies over the past two decades, has been controversial in some countries.

(Reporting by Roxanne Liu in Beijing and Miyoung Kim in Singapore; Editing by Nick Macfie)