More than 150 BBC staff have signed a letter protesting about plans to introduce advertising on the international version of the corporation's news website.
The letter, which has been sent to the BBC director general, Mark Thompson, says any move to include ads would damage the corporation's global reputation for impartiality and distinctiveness.
Signatories include senior television correspondents Caroline Wyatt, David Willey and Mike Wooldridge as well as editors, writers and designers in the news interactive department.
"This goes to the heart of why the BBC has an unparalleled reputation abroad for trustworthiness," BBC business editor for news interactive, Tim Weber, who also signed the letter, told in-house magazine Ariel.
"Being a space that is free of advertising is for us a unique selling point. If the BBC doesn't see reason we could become saddled with something that we will live to deeply regret."
The international news site, which is mainly funded by the Foreign Office as part of its World Service grant, is due to be transferred to the BBC's commercial offshoot, BBC Worldwide, which is charged with maximising revenues.
Critics have said government money would dry up if advertising was included, while commercial rivals would also complain about the BBC further encroaching on their businesses.
The BBC director of global news, Richard Sambrook, said the decision was of "strategic importance" and was receiving "prolonged consideration" at senior level.
"Just as 12 years ago we had to chose between launching BBC World as a global TV news channel commercially or having no channel at all, today we have to consider how we can best support the BBC's global purpose in the on-demand age as the competition develops rapidly."
It is likely non-news pages on the new bbc.com website will include banner advertising, while a decision on the more contentious issue of adverts on the news site is expected to be taken tomorrow by the BBC journalism board, with its recommendation going to the executive committee and then the governors for approval.
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