The search is being handled by creativebrief. The original brief asked agencies to create a branding strategy for the service, which is likely to be launched under the name of SeeSaw, as well as a national advertising campaign.
However, the process is understood to have been hampered by this week's decision by the Office of Fair Trading to refer the service to the Competition Commission.
The new broadband service was due to go live this year, providing programming on demand for the three channels. However, the launch will now be delayed until 2009 while the regulators decide whether it raises potential competition concerns.
A spokeswoman for Kangaroo denied that the service was searching for an advertising agency and said that all plans were on hold pending the verdict of the Competition Commission.