More than 3,100 pregnant Colombian women are infected with the mosquito-borne Zika virus, President Juan Manuel Santos said on Saturday, as the disease continues its rapid spread across the Americas.

The virus has been linked to the devastating birth defect microcephaly, which prevents fetus' brains from developing properly. There is no vaccine or treatment.

There are so far no recorded cases of Zika-linked microcephaly in Colombia, Santos said.

There are 25,645 people infected with the disease in Colombia, Santos said during a TV broadcast with health officials. Among them are 3,177 pregnant women.

"The projection is that we could end up having 600,000 cases," Santos said, adding there could be up to 1,000 cases of Guillain-Barre syndrome, a rare but serious condition that can cause paralysis and which some governments have linked to Zika infection.

Authorities and community leaders will be working across the country to fight mosquitoes - fumigating and helping families rid their homes of stagnant water, the president said.

Colombian health minister Alejandro Gaviria has said he believes three deaths are connected with Zika.

The province of Norte de Santander had nearly 5,000 cases of the virus, more than any other in the country, an epidemiological bulletin from the national health institute showed.

Unreported cases and patients with no symptoms of infection could mean that there are between 80,000 and 100,000 current Zika infections in Colombia, Gaviria has said.

An estimated 80 percent of those infected with Zika show no symptoms, and those that do have a mild illness, with a fever, rash and red eyes.

There is no vaccine or treatment for Zika, which is a close cousin of dengue and chikungunya and causes mild fever, rash and red eyes.-Reuters