Disney would only be forced to make such an offer if it completes a deal to buy Twenty-First Century Fox TV and film assets, which include a 39 percent stake in Sky, before either Fox or rival suitor Comcast succeed in taking control of the British broadcaster.

The price is designed to reflect the level of the offer Disney is making for Fox, and its holding in Sky.

The regulator had set the level of a possible mandatory Disney offer for Sky at 14 pounds a share on July 13. But it has had to hold a series of hearings since then to review the level after a number of groups appealed the decision.

(Reporting by Kate Holton; editing by David Evans)