Indonesian authorities have yet to receive additional details about the Japanese man who reportedly tested positive for the novel coronavirus disease (COVID-19) shortly after visiting Indonesia, ministry officials said.

The Health Ministry's Disease Control and Environmental Health Directorate General secretary Achmad Yurianto said that although the ministry had contacted the Indonesian Embassy (KBRI) in Tokyo about the man, they were still unable to verify his identity.

“We don’t know his name or which part of Indonesia [he visited]. So what can we investigate?” Yurianto told The Jakarta Post on Sunday.

Previously, Japanese public broadcaster NHK reported that the Tokyo metropolitan government announced on Saturday that the man, a Tokyo resident in his 60s, had been infected with the novel coronavirus.

Read also: Japanese man tests positive for COVID-19 after Indonesia visit: Report

He had reportedly visited Indonesia from Feb. 15 and was hospitalized upon his return to Japan on Feb. 19 with severe difficulty breathing, and is said to be in a "serious condition". The NHK did not specify the man’s destination in Indonesia.

Foreign Ministry acting spokesperson Teuku "Faiz" Faizasyah said there had been no official communication from the Japanese authorities about the man.

“That’s the problem, until now there has been no information yet from Japan,” Yurianto said.

Bayu Krisnamurthi, who headed the National Committee for Avian Flu Control and Pandemic Preparedness between 2006 and 2010, said that people infected with the coronavirus outside Indonesia could spread it inside the country through droplets from coughs and sneezes.

“The health authorities should quickly clarify this case. It should be assumed that the virus could have been transmitted to someone else before the symptoms appeared,” Bayu told the Post.

Meanwhile, Amin Soebandrio, the director of the Eijkman Institute for Molecular Biology said that if the Japanese man showed no symptoms during his stay in Indonesia he could be undetected despite already carrying the virus during the incubation period, which is up to 14 days.

“This is not just in Indonesia. [The man would be undetected] in any country if no symptoms were shown before he returned to Japan,” Amin told the Post.

Amin also said that the Indonesian government had followed proper procedures according to the World Health Organization (WHO), including requiring health cards and quarantining travelers who recently visited China.

“So the problem is not in our ability to detect [the coronavirus] or not, because we have put all the measures in place,” Amin said.

There have been no confirmed cases of COVID-19 in Indonesia to date.