Thai health authorities have reported the first two confirmed cases of microcephaly linked to mosquito-borne Zika, as the US issued a travel alert for entire Southeast Asia region.
"Two of three infants tested had microcephaly due to the Zika virus," said health ministry spokesperson Wicharn Pawan.
The Department of Disease Control refused to disclose the location of the affected infants but confirmed it was not in Bangkok.
The World Health Organization said this was the first case of Zika-linked microcephaly in Southeast Asia.
"Countries across the region must continue to strengthen measures aimed at preventing, detecting and responding to Zika virus transmission," Dr Poonam Khetrapal Singh, WHO regional director.
Microcephaly in babies can lead to developmental and respiratory problems.
The US Centers for Disease Control issued a travel alert for all ASEAN nations and the Maldives including Brunei, Myanmar, Cambodia, Indonesia, Laos, Malaysia, Maldives, the Philippines, Timor Leste and Vietnam.
The CDC issued a similar travel warning for Singapore last month.
"CDC recommends pregnant women should consider postponing nonessential travel to Southeast Asia countries with reports of Zika virus infection from local transmission or related to travel to those countries, and those countries with adjacent borders where limited information is available to fully evaluate risk of Zika virus infection," it said.
