LONDON (Reuters) -Britain will require social media companies to take action to stop child abuse on their platforms, and if necessary work to develop technology to scan encrypted messages as a last resort, technology minister Michelle Donelan said on Thursday.

Platforms including Meta's WhatsApp and Signal have been fighting Britain's Online Safety Bill, which is currently being scrutinised by lawmakers, because they say it could threaten the end-to-end encryption that underpins their messaging services.

Junior minister Stephen Parkinson appeared to concede ground to the tech companies' arguments on Wednesday, saying in parliament's upper chamber that the Ofcom communications regulator would only require them to scan content where "technically feasible".

Tech companies have said scanning messages and end-to-end encryption are fundamentally incompatible.

Donelan, however, denied on Thursday that the bill had been watered down in the final stages before it becomes law.

"We haven't changed the bill at all," she told Times Radio.

"If there was a situation where the mitigations that the social media providers are taking are not enough, and if after further work with the regulator they still can't demonstrate that they can meet the requirements within the bill, then the conversation about technology around encryption takes place," she said.

She said further work to develop the technology was needed, but added that government-funded research had shown it was possible.

(Reporting by Paul Sandle and Muvija MEditing by Helen Popper)