A bid from 21st Century Fox to acquire Sky has been challenged by US cable company Comcast.

Comcast, who already own NBC and Universal Pictures, has made a £22.1 billion offer to buy Sky.

Fox has already proposed a deal to buy the remainder of Sky that it doesn't already own for a cost of £18.5 billion. Fox already own 39% of Sky and are looking to acquire the remaining 61%.

However last month the proposed acquisition was provisionally ruled to not be in the public interest, with the Competition and Markets Authority ruling that if the Fox / Sky deal went through, Rupert Murdoch would have too much influence and power in the UK media.

Murdoch also owns News Corp which publishes the Times, The Sunday Times and The Sun newspapers.

Comcast chief executive Brian Roberts said: "We would like to own the whole of Sky and we will be looking to acquire over 50% of the Sky shares."

He also described Sky as an "outstanding company" and said he was "confident" Comcast's offer would be approved by regulators.