A pre-dawn landslide on Wednesday, triggered when the rain-swollen Dagua River overflowed its banks, devastated an area of the Valle Del Cauca department, between Cali, its capital, and the port of Buenaventura.
Since then 15 landslides, five of them massive, have been recorded in the area.
According to official figures, 11 people were killed -- including a reporter who was covering the disaster -- and 40 people remain missing.
The social protection minister, Diego Palacio, said that despite the major rescue operation under way, the number of deaths "could reach 50".
"We have recovered 11 bodies, but are extremely worried about the high number of missing. After hours and in spite of their efforts, aid teams have not been able to rescue the more than 40 people who are missing," Mr Palacio said.
Five army and air force helicopters helped evacuate the Buenaventura area, rescuing victims who had lost their homes, their clothes ripped off by the violent mudslides.
President Alvaro Uribe ordered the evacuation of around 1,200 tourists by government aircraft after surveying the stricken area by air.
"We will concentrate this Good Friday, so that my God helps us to see how we respond" to the tragedy, the president said.
"We are going to muster all our strength."
Mr Uribe said he is considering declaring an economic emergency in the area, a move that would free public money to aid the more than 700 people affected in the disaster and speed recovery efforts.
The disaster has caused heavy economic losses in the Andean country as roads to the port that normally see 100 cargo trucks a day remain blocked.
The tourism sector also has been hit. A hotel association noted there had been 20,000 confirmed hotel reservations for Holy Week, but only 1,200 tourists at Pacific seaside towns were waiting to be evacuated.