The mosquito-borne virus has been detected in 70 countries worldwide so far, suggested the World Health Organization (WHO). Zika infections were "highly likely" to keep spreading across Asia, the WHO announced.
WHO director Margaret Chan said experts were still looking for ways to deal with the virus, the BBC reported.
"Unfortunately, scientists do not yet have answers to many critical questions," she told an annual regional WHO meeting in the Philippines capital, Manila.
Zika generally has mild effects but is more dangerous for pregnant women as it has been linked to severe birth defects, including the brain deformation microcephaly.