The decision affects incumbents Starcom, Upstream Asia and Tequila, which won the account in April (Media, 23 April).
An O2 spokesperson denied marketing budgets would be cut, adding that focus would fall on the Atom range.
However, a source said that at least four products and associated campaigns were slated for the remainder of the year.
Since the beginning of the year, John Featherstone, VP of O2 Oceania, departed for rival HTC, while senior marketing manager of O2 Asia, Winnie Phua, joined the Singapore Tourism Board.
