Japan's health minister Katsunobu Kato says his ministry is working to identify the infection routes of the new coronavirus after the first virus-related death in the country on Thursday.

Kato told reporters on Friday that people must be concerned about becoming infected.

Japan's transport ministry says it has finished test flights above central Tokyo on new routes to the capital's Haneda Airport.

The new flight paths are due to open on March 29 to increase international slots at Haneda ahead of this year's Tokyo Olympics and Paralympics.