BANGKOK - Thai authorities have confirmed that two cases of babies with microcephaly - abnormally small heads - were caused by the Zika virus, the first time the linkage has been made in Southeast Asia.

A World Health Organization statement on Friday urged countries in the region to take stronger measures to contain the virus after Thai health officials announced the linkage was confirmed in two of three cases of babies afflicted with microcephaly.

The UN agency had earlier said the cases, if confirmed, would be the first of Zika-associated microcephaly in Southeast Asia.

The virus causes the birth defect when pregnant mothers are infected. The disease is most widely spread by mosquitoes, and WHO is urging private citizens as well as governments to take strict mosquito control measures.