TOKYO: Japan's Emperor Naruhito is set to declare the opening of the Tokyo Olympics on Friday, reprising the role of his grandfather who opened the last Tokyo Olympics in 1964.

Those Games were enthusiastically embraced in Japan and abroad, and heralded a new era for the nation after it emerged from the devastation of World War II and was on its way to becoming an economic powerhouse.

This time, the Tokyo Olympics have been greatly complicated by the COVID-19 pandemic and battered by a series of scandals. Public opinion polls consistently show that a majority of Japanese are against holding the event during the pandemic.

The head of the Imperial Household Agency said late last month that Emperor Naruhito "appears concerned" about the possibility the Olympic Games could cause the coronavirus to spread as feared by many members of the public.

While the 61-year-old emperor's concern was framed as the official's impression rather than something he explicitly expressed, the rare revelation into the monarch's thinking stirred speculation he had worries about the holding of the Olympics during the pandemic.

The Olympic Charter, however, stipulates that the Games be proclaimed open by the head of state of the host country, meaning his presence is required.

The head of the International Olympic Committee met with the emperor on Thursday and assured him organisers were doing their utmost not to bring infections into the country.

The Oxford-educated monarch is expected to attend the ceremony without Empress Masako or other members of the imperial family, after organisers banned spectators.

When his grandfather, Emperor Hirohito, declared the 1964 Games open, he was accompanied by Empress Nagako.

The Olympic charter also specifies the exact wording to be used for opening, including the word "celebrate".

There has been speculation that because of the pandemic, the emperor will use a more neutral word in Japanese that can still be translated as "celebrate" in English.

The emperor has no political power but is widely respected as a figurehead in Japan.