SANTIAGO, March 15 (AFP) - A vast area of earthquake-hit Chile, including the capital city of Santiago, was plunged into darkness Sunday by a massive blackout, the National Emergency Office said.

The area without power covered a 2,000-kilometer (1,200 mile) stretch, starting in the region of Atacama, north of Santiago to Chiloe Island, south of the capital, officials said.

It affected about 80 percent of Chile's population of 17 million people.

Power went out in the capital just before 9:00 pm local time (0000 GMT Monday), and there were problems with phone service reported as well.

Several metro stations and shopping centers were closed while a benefit concert to collect funds for victims of the quake was suspended.

About 20 metro trains were immobilized inside tunnels and their passengers had to be evacuated, according to Clemente Perez, director of the Santiago metro.

"The passengers were a little scared, but the evacuation proceeded normally," he said.

Authorities said the blackout was likely related to the massive 8.8-magnitude quake that rocked central Chile on February 27, or to the numerous aftershocks that have shaken the country since.

"The blackout was most probably the result a of a weakness in the power grid caused by the earthquake," Cristian Larroulet, secretary general of the president's office told reporters. "It was one more consequence of the tremor that shook our country."

He said power was gradually returning to the affected area and predicted the service would be restored in about three hours.

According to Interior Minister Rodrigo Hinzpeter, the most serious breakdown occurred in a transformer located near the town of Temuco, about 600 kilometers (375 miles) south of here.

The minister urged residents of the affected area to remain calm and to refrain from leaving their homes without need.

The February 27 quake sparked a killer tsunami and left almost 500 confirmed dead and some two million people affected, according to the government.

Newly installed Chilean President Sebastian Pinera estimated last week it would cost 30 billion dollars to rebuild the nation after the devastating quake.

Pinera took office on Thursday in the midst of a series of powerful aftershocks that triggered a tsunami alert, worried world dignitaries in attendance and caused a brief panic at parliament in the coastal city of Valparaiso where the inauguration took place.