Zika infections are "highly likely" to keep spreading across Asia, the World Health Organization (WHO) has warned.

Hundreds of cases of the virus have been reported in Singapore while two cases of Zika-linked microcephaly have already been confirmed in Thailand.

The mosquito-borne virus has been detected in 70 countries worldwide, at least 19 in the Asia Pacific region.
WHO director Margaret Chan said experts were still looking for ways to deal with the virus.

"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.

The virus has existed in Asia for decades, but the latest large-scale outbreak originated in Brazil.