Japan is set to approve on Wednesday test kits that can detect novel coronavirus antigens in 15 to 30 minutes as the country seeks to improve its testing regime, government sources said Saturday.

The government will cover the new test under Japan's public insurance system, the sources said.

(Supplied electron micrograph shows the new pneumonia-causing coronavirus.)[Courtesy of the U.S. National Institute of Allergy and Infectious Diseases]

Fujirebio Inc., the test kit producer, said it can supply 200,000 kits a week and will expand output if there is more demand.

After the Tokyo-based company applied for approval in April, health minister Katsunobu Kato told parliament on Friday he would make a decision "within the next week."

"They can be used at the medical front. The maker said a sizable number (of the kits) can be provided," he said.

Antigen tests, which detect proteins unique to a virus, are widely used for testing for flu. Doctors insert swabs into the back of a patient's nostril and get the results on site.

In contrast, the currently dominant polymerase chain reaction tests require sending samples to labs and waiting hours for results. In some cases, patients have to wait for a week to learn the outcome.

But the antigen test is said to be less accurate, and patients with a limited amount of virus could test negative.

"We will cover its shortfalls with PCR tests, and consider how to use it in the best combination," said Kato.

He indicated the new test is useful for testing patients requiring immediate medical attention as well as those getting ready to undergo operations.

Prime Minister Shinzo Abe has also suggested using the antigen test prior to using PCR tests.