In a rare television address on Wednesday, Japan's Emperor Akihito expressed deep concern over the escalating nuclear crisis his nation faces and said he is praying for people's safety after last week's earthquake-tsunami disaster, the Associated Press reports.

The 77-year-old emperor, who commands great personal respect in Japan, thanked domestic and foreign emergency personnel for their efforts to locate the many missing amidst difficult conditions in the affected area, "The number of people killed is increasing day-by-day and we do not know how many people have fallen victim."

"People are being forced to evacuate in such severe conditions of bitter cold, with shortages of water and fuel..." he said. "I cannot help praying that rescue work is done swiftly and people's lives get better, even a little. I pray for the safety of as many people as possible."

Akihito also said he was "deeply concerned" about the "unpredictable" situation at the quake-damaged Fukushima No.1 nuclear power plant, where the quake knocked out reactor cooling systems. A series of explosions followed.

"I sincerely hope that we can keep the situation from getting worse," Akihito said.

"I have received messages of condolence from heads of state of various countries with kind words that their hearts are with the victims. Allow me to convey the words to people in the afflicted areas."

In a show of solidarity with the residents of Japan's capital, who are currently subject to power rationing, Emperor Akihito and Empress Michiko ordered the Imperial Palace's electricity to be turned off for two ours per day, Kyodo News reported.

A spokesman for the Imperial Household Agency said it was the first time the emperor had addressed the nation on television in the wake of a natural disaster. After the earthquake in Kobe in 1995 which killed more than 6,400 people, Akihito issued a written statement rather than making a televised address.

Akihito acceded to the throne in 1989 following the death of his father Emperor Hirohito. As the titular head of state in Japan, he plays a ceremonial role.

As of Wednesday, the toll of the dead and missing from the 9.0-magnitude quake and tsunami that hit Japan's northeast coast has topped 11,000, with 3,676 confirmed dead and 7,558 unaccounted for, according to Japan's national police agency.