The media company is expected to invite agencies to pitch for the business following differences with i-level.
Sky appointed i-level to work across its online media business in May 2005, with a brief to help grow subscriber numbers. However, the relationship is said to have deteriorated in recent months.
In March, Sky called a pitch for its search business, which resulted in the appointment in August of Diffiniti to handle search engine optimisation activity and Unique to work on pay-per-click.
Online spend has increased as a result of its battle for subscribers with Virgin Media and as part of large-scale campaigns such as "See Speak Surf" and "Believe in Better".
Sky's online activity is a key part of its constant work to increase subscriber levels. In the year to 30 June, Sky added a net 406,000 customers, taking it to a total of 8.6 million.
