The Colombian government is grappling with providing migrants with their basic needs such as food, shelter and medical care.
The number of Venezuelans living in Colombia jumped 62 percent in the last half of 2017 to more than 550,000, its migration authority said on Friday, as Venezuela's economic devastation hastens migration to the neighboring country.
Most of the Venezuelan migrants lack visas and have fled food shortages and the world's steepest inflation by crossing the 2,219 km (1,379-mile) porous border to Colombia.
While Venezuelan engineers work in Colombia's oil industry and many professionals have flocked to the capital city Bogota, a growing number of poor people from that country have settled in Colombian border towns.
In Cucuta, close to the Venezuelan border, many sleep in parks and wash their laundry in creeks.
The influx has forced Colombia to grapple with migrants arriving in need of food, shelter and medical care, often given at the government's expense.
Venezuela's Information Ministry did not immediately respond to a request for comment.
More than 650,000 Venezuelans passed through Colombia on their way to other countries or returned home during 2017, the authority said in a report.
"Close to 60 percent of Venezuelan citizens who left our country left for destinations other than Venezuela," migration head Christian Kruger said in the report.
About 1.3 million Venezuelans have registered for a special migration card that allows them to cross the border by day to buy food and other products that are scarce in their own country.
On an average day in 2017, more than 30,000 Venezuelans used the cards to enter and leave Colombia across the land border, where smugglers thrive by selling increasingly unavailable but heavily subsidised Venezuelan products to Colombians.
Of those Venezuelans living in Colombia, 126,000 have legal permission to stay, including some 69,000 who have taken advantage of a humanitarian visa introduced in July, the report said.
The UN is willing to send more aid to Colombia to help the country cope with the arriving migrants, Secretary General Antonio Guterres said on a visit to the Andean country last week