The Philippine Department of Transportation and Communication said Wednesday that ASEAN countries were expected to sign a multilateral air agreement.

The Association of South East Asian Nations (ASEAN) countries signed among themselves together with China, India, Japan and Korea an air agreement to be effected in December this year, DOTC Chairman Leandro Mendoza said.

Mendoza, together with Manila International Airport Authority General Manager Alfonso Cusi, was interviewed Monday night by reporters and discussed the plan.

Mendoza said the Philippines and other ASEAN countries have agreed in principle to liberalize their skies with the possible signing of a "common air agreement" in December this year.

Mendoza said ASEAN countries have also discussed with China, India, Japan and Korea the possibility of their joining in the regional air services grouping.

Cusi said ASEAN's adoption of an open skies policy would ultimately lead to the creation of a single aviation market in the region by 2015, wherein the Philippines needs to further develop its air transport policy as well as upgrade existing facilities.

Mendoza and Cusi said that member-countries that include Malaysia and Thailand have already been developing airports with multiple runways to accommodate bigger traffic while the Philippines still has to develop one.