Bob Bowlsby, the commissioner of US college sports’ Big 12 Conference, has warned the value of its media rights could drop by 50 per cent once the University of Texas and University of Oklahoma join the Southeastern Conference.

Bowlsby has been hugely critical of the schools after their recent decision to switch conferences from 2025, and accused them of plotting the move for several months.

He also claimed ESPN was involved behind the scenes and sent a letter to the major US broadcaster accusing it of trying to “destabilise” the league.

The Big 12’s present 13-year media rights deal with ESPN and national network Fox is worth $2.6 billion.

At a hearing with a committee of Texas senators on Monday, Bowlsby said this figure would be cut in half once the American football teams Texas Longhorns and Oklahoma Sooners join the SEC.

The Big 12 distributed $345 million to its 10 members this year ($34.5 million each), down from the previous year because of the pandemic. The majority of that revenue comes from the conference’s TV deals.

Texas and Oklahoma formally accepted invitations to join the SEC earlier this week after notifying the Big 12 that they will not renew their grants of media rights beyond 2025.

The schools are not expected to officially join the SEC until 1 July, 2025 with full athletic participation in the 2025-26 academic year.