Japan is only using a sixth of its capacity to test for the new coronavirus even as it is increasing its ability to do so, government data shows, adding to concerns it is understating its outbreak and not doing enough to contain it.

Nationwide capacity for the polymerase chain reaction (PCR) test has grown to 7,500 a day, on track to reach an 8,000 a day target by the end of the month.

But the number of tests conducted has been on average 1,190 a day over the past month, for a total of 32,125, according to health ministry data.