People over 75 may be asked to give up their free TV licence or make a voluntary contribution to it, under plans being considered by the BBC.

The corporation must absorb the loss of £650m worth of licences for over-75s from 2020 as part of a funding deal agreed with ministers last year.

A report on ways to appeal for voluntary contributions is due in 2016.

The BBC has refused to comment on suggestions that older celebrities might front a publicity campaign.

The Times reported that such a campaign could be run by personalities such as Sir Michael Parkinson and actress Dame Helen Mirren.

'Loophole'

Historically, the government has met the cost of free licence fees for over-75s, transferring the money to the BBC annually.

In 2013-14 the total bill for the government was £608m, which amounted to about a fifth of the BBC's budget.

The corporation's responsibility for the free licences will be phased in from 2018-19, with the full liability met by the BBC from 2020-21.

At the time of the announcement in July, the BBC said it was the "right deal... in difficult economic circumstances".

In return, the government agreed the corporation could ask for voluntary payments from those who currently receive free licences.

Ministers also agreed the BBC could look into ways of closing the "iPlayer loophole", which at present means that if people only watch catch-up TV and do not watch any live TV, they do not need a licence.

The BBC has said, though, that there is no proposal to make people pay to watch catch-up TV on iPlayer on top of the licence fee.

* £271.4m of the total licence fee pot is used by the government to fund Welsh language channel S4C, the local TV scheme and broadband rollout.

Labour peer Dame Joan Bakewell - formerly a government-appointed champion of the elderly - told BBC London the licence fee represented "enormous value for money" for pensioners, adding that those who had the means to pay should do so.

But she said the BBC should not be in a situation where it had to ask.

"The government pulled a fast one recently because what they did was this... transgress from one enterprise, which is government policy about [cutting] welfare, into the BBC's licence fee - which is a completely original and outrageous undertaking."

Roger Laughton, a former BBC and ITV executive, agreed the BBC was "between a rock and a hard place".

But Dot Gibson, general secretary of National Pensioners, warned the corporation against using celebrities to try to persuade ordinary pensioners to give up their free licence.

"Many older, vulnerable people might be taken in by this when they should be protected," she said.

"The government needs to take back responsibility for the free TV licence or we're going to see it cut by stealth and then eventually removed altogether."

The BBC confirmed that Frontier Economics, a consultancy led by former cabinet secretary Lord O'Donnell, would report back within months on the best approach to asking people for contributions.

It said it would then "look at the best way forward, including whether to run a campaign".