TalkTalk has called on the government to stop using telecoms consultancy Analysys Mason, due to its links with BT.
Broadband Delivery UK (BDUK), part of the Department for Culture, Media and Sport (DCMS), uses the consultancy, but so too does BT.
TalkTalk is therefore concerned about potential conflicts of interest and a possible perception that "BT is being favoured due to holding influence over BDUK's advisers".
The company has raised its objections in a letter to BDUK Chief Executive Chris Townsend, which was copied to Digital and Communications Minister Matt Hancock, the Telegraph reports.
One specific concern related to a recent report by Analysis Mason for BT, which said it was highly unlikely that any new ultrafast broadband network would succeed.
TalkTalk pointed out that it has built a new ultrafast network in York and plans to expand elsewhere.
As a result, it believes the report was designed to bolster BT's efforts to block Ofcom's plans to make the market more competitive.
Earlier this year, the regulator published its Strategic Review of Digital Communication, which outlined a strategy to promote the rollout of ultrafast broadband facilities on a large scale, based on cable and fibre lines.
One of its key recommendations was to support investment by rival providers to make the market more competitive and reduce the country's reliance on BT's infrastructure subsidiary Openreach.
"An organisation which is writing pieces which purport to demonstrate that we will not be able to build a competitive fibre network… is likely as a matter of course to give less weight to our views than to the views of its client BT," TalkTalk said.
"Our primary concern… [is] that Analysys Mason is likely to place more weight on BT’s evidence, as their client, than on any evidence which may conflict with BT’s view.
TalkTalk added that Analysys Mason’s findings in its report for BDUK could potentially "be influenced by its desire to secure more commercial work from BT".
A DCMS spokesperson said: "Analysys Mason was awarded the contract following a fair and transparent open tender process.
"BDUK was aware of Analysys Mason's work for BT, and robust controls are in place to prevent any conflict of interest."