MANILA, Oct. 11 (Xinhua) -- Zika virus infection is "highly likely to further spread" in the western Pacific region, the World Health Organization said on Tuesday, expressing concern over the possibility that complications associated to the virus might increase.

"It is highly that the region will continue to report cases and possibly new outbreaks of Zika virus infection," the WHO said in a report.

The report added, "Considering the uncertainties, the possibility of observing complications associated with Zika virus infection may increase."

Since 2007, countries and territories have reported evidence of mosquito-borne Zika virus transmission.

Many of the reported cases were reported in 2015, according to the report. "Countries and territories with reported Zika virus outbreak from 2015 onwards," the report said.

Indeed outgoing WHO director general Margaret Chan said ZIKA cases in the region "are on the rise." In fact, she said that ASEAN health leaders "have expressed their concern."

"Unfortunately, scientists do not yet have answers to many critical questions," Chan said.

The report stressed the need to strengthen "existing surveillance systems to promptly detect cases and complications."

WHO also recommended to strengthen or establish systems to provide care, services and support to affected individuals, families and communities.

Another recommended action is to "establish or strengthen systems to contribute to imposing understanding of Zika through supporting research."

WHO officials in the Western Pacific region are meeting in Manila to develop a long-term strategy to mitigate the impact of Zika health threat.

"The action plan will help us combat not only dengue, but also other arboviral diseases transmitted by Aedes mosquitos, including Chikungunya and Zika," WHO Regional Director for the Western Pacific Shin Young-soo said.

Though Zika has been more prevalent in the Americas, Shin stressed that the first outbreak reported was in the Federated States of Micronesia in 2007.

The meeting this week in the 67th session of the regional committee, WHO's governing body for the Western Pacific region, which includes 37 countries and areas from China in the north and west, to New Zealand in the south, and French Polynesia in the East.

The committee consists of representatives from the region's member states and associate members who meet annually.