Last week, Sky received approval from regulators in the Republic Of Ireland for its purchase of VMtv, which operates the Living, Bravo and Challenge brands.
However, the OFT now plans to investigate the deal to see whether it could constitute a qualifying merger under the 2002 Enterprise Act.
The watchdog has today invited interested parties from the industry to comment on the sale, including its potential impact on the pay-TV market.
Should the OFT decide that there are potential concerns regarding competition, it will refer the case to the Competition Commission for a more thorough investigation.
Also today, Virgin Media has confirmed plans to launch Sky Sports 1 HD and Sports 2 HD on its cable TV platform as part of carriage agreements with Sky around the VMtv deal.