The talks come as BT races to finalise more details around its £12.5bn takeover of EE, which it hopes to be able to present on Friday with its third quarter results.
However, sources with knowledge of the due diligence being carried out cautioned that the announcement is looking unlikely to meet this deadline.
Sky has so far remained an outlier in the wave of acquisitions looking to transform the UK telecoms market in 2015. The company was linked to takeover talks with O2 earlier this year, but Three’s Chinese owner Hutchison Whampoa on Friday confirmed it has entered exclusive £10bn talks with O2’s Spanish owner Telefonica.
The final question in the mix this week is the regulatory one. Both BT and Three’s takeover deals would attract the attention of the UK’s Competition and Markets Authority, media regulator Ofcom, and could be large enough to prompt European regulators to examine the competition impact in what is a rapidly-converging UK market.
Sky and BT declined to comment.