China’s Hubei province, the epicentre of the coronavirus outbreak, reported a further 4,823 cases of the disease early on Friday morning, bringing the total in the mainland to 64,627.

Deaths in the country caused by the disease, now officially known as Covid-19, reached 1,483 after the province’s health commission announced a daily increase of 116.

Current as of midnight on Thursday, the figures were the second daily batch to be released since the roll-out of expanded diagnostic criteria, under which a diagnosis based on an analysis of symptoms is considered a confirmed case.

The inclusion of clinical diagnoses in the official count led to a dramatic spike in confirmed cases and deaths, appearing to confirm suspicions that the true number of cases far eclipsed the official figures of the past few weeks. The official data had been constrained by the availability of diagnostic tests.

The new monitoring protocol coincides with a purge of top party officials in Hubei, where local authorities have become a target of nationwide public fury over the government’s response to the outbreak.

Wuhan, Hubei’s capital and the site of the seafood and meat market where the contagion is thought to have broken out, reported more than 3,900 new cases and 88 more deaths on Friday.

The coronavirus has infected more than 65,200 people worldwide and spread to two dozen countries. To date, three people outside mainland China have died from the disease, in Hong Kong, the Philippines and Japan.

In the US, which recently announced its 15th case of the virus, the chief of the Centres for Disease Control and Prevention (CDC) confirmed on Thursday that the disease could be transmitted by carriers showing no symptoms.