President Bachelet said the government had increased to 14,000 the number of troops dispatched to patrol restive areas. She appealed to the public for calm amid widespread looting.
"We understand your urgent suffering," said Bachelet, "but we also know that these are criminal acts that will not be tolerated."
The troops in quake-hit areas have also been assigned the job of distributing relief materials.
Residents slept out for a third night in Concepcion, still rattled by aftershocks. There were more than 120 aftershocks with magnitudes greater than 5 on the Richter scale since Saturday.
The deputy interior minister said that the government had purchased all the food in Concepcion's main supermarkets so that it could distribute food for free and that more supplies were being shipped in from elsewhere.
State television reported that more than 300 bodies had been found in a fishing village along the coast where it was swamped by huge tsunami waves immediately following the earthquake.
Quake-caused damages to Chile are so far estimated to be up to 30 billion U.S. dollars, or a fifth of the country's gross domestic product.
Chilean civil aviation authorities announced Tuesday that the flights flow has been normalized gradually at Santiago's international airport Arturo Merino Benitez.
The General Direction of Civil Aeronautics (DGAC) of Chile said the improvement should be attributed to "the coordination and the wills" of related services, including police, customs, services of agriculture and livestock, the concessionaire of the terminal and several companies operating at the airport.
The normalization of flights flow was achieved one day earlier than predicted by the DGAC.
U.S. State Secretary Hillary Rodham Clinton arrived in Chile on Tuesday to offer relief assistance. She brought with her 20 sets of satellite phones.
Clinton arrived from Argentina where she paid a visit after including the country to her itinerary in the ongoing Latin America tour.
"One of the biggest problems has been communications," said Clinton at the airport, "They can't communicate into Concepcion and some of the surrounding areas."
Bachelet has asked for field hospitals, water purification systems, field kitchens, mobile bridges and electricity generators among other relief assistance from the international community.