Colombian health officials say they believe three people have died after contracting the Zika virus and developing a rare nerve disorder called Guillain-Barre.
The announcement on Friday is the first instance in which health officials have directly blamed the mosquito-borne Zika virus for causing deaths.
"We have confirmed and attributed three deaths to Zika," Martha Lucia Ospina, head of Colombia's National Health Institute, said.
"In this case, the three deaths were preceded by Guillain-Barre syndrome. Guillain-Barre is a rare disorder in which the immune system attacks the nervous system."
READ MORE: In search of answers on the Zika outbreak in Brazil
Cases of Guillain-Barre, which causes weakness and sometimes paralysis, have increased in tandem with the outbreak of the Zika virus currently sweeping Latin America.
The timing has raised health officials' suspicions that the neurological condition is a complication of the mosquito-borne virus.
Zika may also be connected to an increase in the number of babies born with microcephaly, or abnormally small heads and brains.
Most Guillain-Barre patients recover but the syndrome is sometimes deadly.
Ospina, an epidemiologist, said another six deaths were under investigation for a possible link to Zika.
"Other cases [of deaths linked to Zika] are going to emerge," she said.
"The world is realising that Zika can be deadly. The mortality rate is not very high but it can be deadly."
Colombia has been hit hardest by the Zika outbreak of any country except Brazil, with more than 20,000 cases, including more than 2,000 pregnant women.
Zika normally causes mild flu-like symptoms and a rash, or goes unnoticed altogether.
But Alejandro Gaviria, Colombian health minister, said the apparent risk of deadly complications was "worrying".
Brazil warns against kissing
Meanwhile, across the eastern border in Brazil, a top health official has cautioned pregnant women to think twice before kissing for fear that it could spread the virus.
Paulo Gadelha, president of the Fiocruz Research Institute in Rio de Janeiro, said scientists have found live samples of the Zika virus in saliva and urine samples.
He said the possibility it could be spread by the two body fluids required further study.
Friday's announcement coincided with the start of Carnival, a five-day-long festival in Brazil, where kissing as many people as possible is a pastime.
Gadelha said that the discovery need not alter Carnival plans for anyone but pregnant women.