Singtel has since terminated the services of social media agency Gushcloud, and its employee who was involved in the marketing campaign that smeared its competitors, Starhub and M1.
In a statement released on its Facebook page, Group CEO Singtel, Chua Sock Koong said: "In June 2014, we worked with a digital agency to promote a youth marketing campaign. We regret that a Singtel employee who worked on this campaign did not adhere to our professional standards and values. We have since terminated the services of the agency and the employee is no longer with us."
Reiterating an earlier apology made to Starhub and M1, Chua added: "Singtel does not condone negative campaigns or publicity against any individual or organisation."
"We are committed to healthy competition in each of our markets. The senior management and I apologise, in particular to M1 and Starhub, that our actions in this incident did not live up to our high standards and values."
The leaked brief gotten Singtel into much trouble, with rival StarHub announcing that it would take legal action against the former.