In a national address on television, Bachelet said 1.5 million people had been affected by the earthquake, while officials in her administration said 500,000 homes were severely damaged.
Meanwhile, at least 100 people were feared trapped inside the rubble of a collapsed building in Concepcion more than 34 hours after the quake struck.
Firefighters and rescue workers used drills and shovels on Sunday to search for survivors amidst the rubble.
"Time is of the essence to save the people inside this building," Jacqueline van Rysselberghe, the city's mayor, said.
Van Rysselberghe also criticised the national government for what she said was a slow response to the quake.
"It's a shame that rescue teams could not come to Concepcion yesterday."
Hours after the earthquake, smaller-than-expected tsunami waves hit Hawaii and the US Pacific Coast. There were no immediate reports of damage and a tsunami warning for Hawaii was soon lifted.
Kevin McCue, president of the Australian Earthquake Engineering Society, told Al Jazeera: "I'm surprised it produced such a small tsunami as a result. But everyone is still on alert right across the Pacific."
Japan issued a warning on Sunday for a tsunami of 10ft or higher and advised coastal residents to evacuate to higher ground.
Bachelet has declared a "state of catastrophe",saying that officials were still trying to evaluate the "enormous quantity of damage."
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The earthquake has raised a daunting first challenge for Sebastian Pinera, who was elected Chile's president in January and who takes office in two weeks.
"Unfortunately, Chile is a country of catastrophes," Pinera said.
He said the disaster heavily damaged many of the country's roads, airports and ports.
At least 214 people were killed and 15 were missing as of Saturday evening.
While that remained the official estimate, Carmen Fernandez, head of the National Emergency Agency, said later: "We think the real figure tops 300. And we believe this will continue to grow."
Local radio reported 100 people were missing in a collapsed building in Concepcion, one of Chile's largest cities with around 670,000 inhabitants.
Aid organisations and government officials in Britain and the US have offered to help Chileans in their efforts to rebuild their country.
Barack Obama, the US president, has said the US has resources in position to deploy should the Chilean government ask for help following the earthquake.
Firefighters rushed to put out fires, and most of the buildings in the city centre were destroyed.
Chilean TV showed images of collapsed homes in Concepcion, a large building completely engulfed in flames and injured people lying in the streets or on stretchers.
|Chilean TV showed images of collapsed homes and burning buildings in Concepcion [AFP]
Some residents looted pharmacies and a collapsed grain silo, hauling off bags of wheat, television images showed.
More than 200 inmates in a prison near Concepcion escaped when walls crumbled, Terra Networks reported.
It also reported that phone lines were either down or busy, making confirmation of damage difficult elsewhere, especially further south towards the epicentre.
The US Geological Survey (USGS) said the earthquake struck 92km northeast of Concepcion at a depth of 63km at 3:34am local time (06:43 GMT) on Saturday.
The earthquake shook buildings in Buenos Aires, Argentina's capital, and was felt as far away as Sao Paulo in Brazil - 1,800 miles to the east.
Dozens of aftershocks
In the capital of Santiago, 320km northeast of the epicentre, three hospitals collapsed while, south of the city, dozen more suffered significant damage, a health official said.
More than 60 aftershocks of magnitude 5 or greater were reported in the hours after the quake.
An earthquake also hit northern Argentina, causing a wall to collapse in Salta, killing an eight-year-old boy and injuring two of his friends, police said.
The USGS said the magnitude-6.3 temblor was a separate, "triggered earthquake" caused by ground waves from the Chilean quake.
In 1960, Chile was hit by the world's biggest earthquake since records dating back to 1900, USGS data shows.
The 9.5 magnitude quake devastated the south-central city of Valdivia, killing 1,655 people and sending a tsunami which battered Easter Island 3,700km off Chile's Pacific seaboard and continued as far as Hawaii, Japan and the Philippines.