SANTIAGO: A huge 8.8-magnitude earthquake rocked Chile early Saturday killing at least 78 people, toppling buildings and triggering a tsunami threatening the Pacific rim of fire, officials said.

The massive quake plunged much of the Chilean capital, Santiago, into darkness as it snapped power lines and severed communications.

AFP journalists spoke of walls and masonry collapsing while people in pyjamas fled onto the streets.

Television images showed destroyed or heavily damaged buildings and debris-strewn streets.

Residents in the south of the city, which appeared to have borne the brunt of the quake, said roads had crumpled and a bridge had been damaged, as an AFP correspondent said buildings "shook like jelly."

The US Pacific Tsunami warning center issued a "widespread" tsunami warning for all Pacific nations.

A partial evacuation of Easter Island has been ordered in Chile in the face of possible big tidal waves, President Michelle Bachelet announced.

She also said two ships with aid had been dispatched to Robinson Crusoe Island, part of the Juan Fernandez Archipelago, which has been affected by a big tidal wave.

Japan's meteorological agency warned of a tsunami risk across large areas of the Pacific including as far away as the Antarctic, as the Philippines warned low-lying coastal areas to prepare for possible evacuation.

Australia and New Zealand issued tsunami alerts while Russia said it was monitoring the risk.

The tremor struck at 3:34 am local time (0634 GMT) when many Chileans were still in nightclubs partying at the start of the weekend.

It was swiftly followed by a series of aftershocks ranging from 5.6 to 6.9 on the Moment Magnitude Scale.

Chilean President Michele Bachelet and her officials rushed to their offices to coordinate disaster relief, state television said, as the powerful aftershocks panicked the quake-prone Latin American country.

"With the quake of this magnitude and given its timing, we cannot rule out other casualties," Bachelet said as first reports came in of deaths.

Santiago lies 325 kilometers (200 miles) northeast of the epicenter of the quake, which hit at a depth of 35 kilometers (21.7 miles).

It struck 100 kilometers (60 miles) northwest of the Chilean town of Chillan, the US Geological Survey said, and 115 kilometers (70 miles) northeast of Concepcion, a city of about a million people.

"Sea level readings confirm that a tsunami has been generated which could cause widespread damage," the US Pacific Tsunami Warning Center said.

Authorities should take "appropriate action," it added, but said the warning did not apply to the west coast of the United States.

"There is a possibility that tsunami will widely occur in the Pacific Ocean," an official for the Japanese meteorological agency said as Australia, New Zealand and the Philippines also issued warnings.

Asian nations have been on heightened alert ever since a massive 2004 tsunami that killed more than 220,000 people around the Indian Ocean.

Japanese Prime Minister Yukio Hatoyama ordered his government to be prepared to offer support for victims if necessary, Jiji Press reported.

"Swift action should be required," Hatoyama told reporters. "It appears to be fairly sizable. I told ministries concerned to be ready to take measures in case relief assistance is needed."

The European Union said it stood ready to provide immediate and coordinated aid for victims.

US seismologists had initially put the magnitude of the tremor at 8.5 but later adjusted it upwards to 8.8.

Earthquake-prone Chile lies along the Pacific rim of fire and is regularly rocked by quakes, but damage is often limited as they mostly hit in desert regions which are sparsely populated.

In May 1960 the country was ravaged what is now known as Valdivia or Great Chilean Earthquake, which was rated 9.5 on the moment magnitude scale.

The resulting tsunami affected southern Chile, Hawaii, Japan, the Philippines, reaching as far as eastern New Zealand and southeast Australia.

The estimated death toll from that disaster ranged from over 2,200 to 5,700.