The US media giant, which owns NBC and Universal Studios, has bid £14.75p a share, following Fox’s £14 a share offer yesterday, which values Sky at £24.5bn.
The new culture secretary, Jeremy Wright, is expected to approve Fox’s proposed takeover of Sky later today. The company is bidding to takeover the 61% of Sky it does not already own.
Comcast’s new offer has won the recommendation of Sky’s independent committee.
Last December Disney announced it wanted to buy the bulk of Fox’s business, including its 39% stake in Sky.
Comcast chief executive Brian Roberts has said the company would be prepared to co-own Sky with either Fox or Disney, as long his company held the majority stake.