Brands are expected to increase their online ad spending in the Asia-Pacific region to $34.6bn in four years, or 26.2% of the total worldwide.

Market research company eMarketer has said that Asia-Pacific will add over half a billion Internet users from 2011 to 2015, for a total of 1.45 billion, making it a prominent market for many consumer-facing brands.

This year, eMarketer estimates online ad spending in Asia-Pacific will reach a total of $19.3bn.

A research commissioned by TNS and Campaign Asia found that digital media, including dedicated websites, sponsored content and ads, increased the interest in a brand among consumers surveyed online.

Across Asia-Pacific, which included China, Hong Kong, Malaysia, Singapore, Taiwan and Thailand, respondents showed an 83.8% increase in interest in using a brand after coming across it in digital media.

Consumers in developing countries, Thailand, Malaysia and China, were more likely than the region as a whole to show an increase in brand interest, at 93.7%, 85.6% and 85.5%, respectively, according to the study.

Word-of-mouth and recommendations from family and friends came out as the most trusted information source, but reviews and brand/product websites were also popular.

Respondents said that some online ads, such as banners, were less trustworthy.