Japan's Emperor Akihito's made a rare televised address after the devastating earthquake and tsunami [REUTERS]

Japan's emperor has appeared on live television to address the nation as it faces the challenge of containing a worsening nuclear disaster in the aftermath of an earthquake and tsunami that killed thousands.

Japanese television stations interrupted coverage of the disaster to broadcast the sombre message in which Emperor Akihito said he was "deeply worried" by the unfolding situation at the Fukushima nuclear plan and said the crisis facing the nation was "unprecedented in scale".

"I am deeply hurt by the grievous situation in the affected areas," the 77-year-old said. "The number of deceased and missing increases by the day and we cannot know how many victims there will be. My hope is that as many people possible are found safe.

"I hope from the bottom of my heart that the people will, hand in hand, treat each other with compassion and overcome these difficult times," he said, urging survivors not to "abandon hope".

Akihito, who ascended to the throne in 1989, is known to give pre-recorded news conferences on set occasions such as his birthday and before overseas trips, but the suddenness of the message, its simultaneous airing on nationwide TV and its content were unprecedented.

For elderly Japanese, the sudden message from the emperor reminded them of a similar broadcast on August 15, 1945, when Akihito's father, Emperor Hirohito, announced the country's surrender in World War Two; the first time a ruling emperor's voice had been heard on the radio.

Conservative Japanese revere the emperor, others feel a fond affection, and still others find the royal family irrelevant.

Miiko Kodama, an expert in media studies said: "This earthquake was worse than the Great Kanto Earthquake (in 1923) ... It's never been experienced before. This is a symbol of that."

She added: "Of course, nothing changes as a result of his message, but for those who believe in the emperor, they will be encouraged."

The emperor and Empress Michiko have long played a role comforting the public in tough times, visiting the survivors of the massive quake that killed 6,400 people in the western port of Kobe in 1995.