There have been desperate scenes as rescuers and family members searched for survivors, often with bare hands.
Teams from Switzerland, Spain and several Latin American countries have arrived to join the search effort.
More than 2,000 people were injured in the quake, Ecuador's most powerful in decades, which hit its Pacific coast.
Earlier, President Rafael Correa warned that the death toll was likely to rise, and said there were still people alive under the rubble of collapsed buildings. He said it was the biggest tragedy to hit Ecuador in the past seven decades.
President Correa visited some of the people affected by the disaster after cutting short a visit to Italy to return to his home country.
"I fear that figure will go up because we keep on removing rubble," a shaken Mr Correa said in a televised address. "There are signs of life in the rubble, and that is being prioritised."
The president warned that the quake will cost Ecuador billions of dollars. It comes at a time when the oil-producing country is already reeling from the slump in global crude prices.
Correspondents say that while the country's energy industry survived the quake mostly intact - the main refinery of Esmeraldas was closed as a precaution - exports of bananas, flowers, cocoa beans and fish could be delayed because of impassable roads and hold-ups at ports.
Foreign Minister Guillaume Long praised those nations which had contributed to the rescue effort.
He tweeted (in Spanish) that as many as 120 mobile rescue teams would be on the ground by Tuesday morning.