TELECOMS watchdog Ofcom has ruled that rivals should not be made to stump up higher charges to share the burden of filling BT’s mammoth pension deficit.

Ofcom said it had seen no compelling evidence that would justify changes to prices set for BT’s wholesale Openreach service to take account of funding for its pension black-hole, estimated at £7.5bn.

The regulator revealed last December it was looking at an option to make firms such as TalkTalk and BSkyB pay up to 4% extra for using wholesale telephony from BT to help cover pension deficit payments.

It was feared consumers would face higher charges if the increases were passed on by operators.

But Ofcom said: “At this stage, Ofcom has not received compelling evidence from stakeholders which would justify a change in approach.

“Therefore, in this second consultation, Ofcom proposes that the current approach to the treatment of BT’s pension costs be maintained.”

Ofcom currently includes ongoing pension service costs, but excludes payments made by BT in respect of its pension fund deficit.

The inquiry was launched last year after BT’s deficit soared and the regulator became concerned the scale of its pension payments could affect its costs.

BT has long lobbied for these charges to be taken into account when Ofcom sets the regulated fees for renting its copper-based land lines to telecoms service providers.

It is paying £525m a year into the pension scheme and is battling with the Pensions Regulator to agree a long-term funding plan.

The group said it would now consider a response to Ofcom’s proposals.

BT’s pension fund gap was calculated at about £9bn at the last triennial review in 2008, although the firm believes the deficit now sits at £7.5bn.

It delivered a blow to customers earlier this week when it said they would have to pay up to 10% more for phone calls on their landline to cover costs and help it recover from the recession. The firm, which has 12.5m phone customers, said it would also increase its monthly line rental by 50p from the beginning of October.

TalkTalk said Ofcom had recognised that consumers should not bear the surcharge, which would have been “unjust and inconsistent” with Ofcom’s economic approach.