BOGOTA - There could be up to 4 million Venezuelan migrants living in Colombia by 2021 if the situation in the socialist-run country worsens, Colombia's foreign minister said on Tuesday, estimating the cost at some $9 billion.

Venezuelans have been crossing into countries across the region to escape food and medicine shortages and a deep economic crisis. Many have settled in Colombia, with which Venezuela shares a porous eastern border.

Nearly one million Venezuelan immigrants already live in Colombia, which has a total population of around 50 million.

Their presence could cost the Andean nation about 0.5 percent of its gross domestic product in healthcare, education and infrastructure spending, the government said last week.

"In a scenario where the situation worsens, we're talking about 4 million Venezuelans in Colombia," Foreign Minister Carlos Holmes Trujillo said at a migration forum in Bogota, citing a worst-case scenario estimate from a government study he said will be published next week. "Resource requirements would be 26.57 trillion pesos ($8.87 billion)."

A Venezuelan woman holds a girl at a health post f A Venezuelan woman holds a girl at a health post for migrants in Cucuta, along Colombia's border with Venezuela, July 16, 2018. A Venezuelan woman holds a girl at a health post for migrants in Cucuta, along Colombia's border with Venezuela, July 16, 2018.

"We're facing the magnitude of this challenge, which our country has never seen before," Trujillo said, adding that under the worst-case scenario, Colombia "would be obliged to make budget allocation adjustments on the order of 10.5 percent in the coming years."

More than 2 million Venezuelans have left their country in recent years, with most arriving in neighboring South American nations, according to the United Nations migration agency.

Affected countries have repeatedly asked for more aid to help them cope with migrants' needs. Many Venezuelans arrive with nothing more than what they can carry.

Venezuelan President Nicolas Maduro and other top officials of the ruling Socialist Party have dismissed those migration figures as stemming from politically-motivated alarmism and "fake news" meant to justify foreign intervention in the country's affairs.