MPs have called on the BBC to "clarify" its data on the scale of licence fee evasion in the UK.
The broadcaster's annual reports identify a rise from 5% ten years ago to between 6.5% and 7.5% today.
The Digital, Culture, Media and Sport (DCMS) committee said the lack of precision means they have been "left asking whether there is something to hide".
It added that the BBC has given more detailed information to Lord Botham on another issue – licence fee figures for the elderly.
The universal right to a free TV licence has ended for all over-75s not in receipt of pension credit.
The DCMS committee's chair, Julian Knight MP, said: "We want the BBC to address real concerns about licence fee evasion - we've heard that current rates are significantly higher than the figures it has published to date.
"When we asked for this information we were pointed to published annual reports that were nowhere near as detailed as what appears to have been sent to Lord Botham about the over-75s. We are left asking whether there is something to hide.
"This matters because there is a real risk that the BBC licence fee funding model could become unsustainable as a result of evasion."
Former cricketer Lord Botham had called for over-75s not to be threatened with legal action over the non-payment of the TV licence.
BBC director-general Tim Davie has signalled his agreement.
