Shadow Health Secretary Andy Burnham said plans to close the A&E department at Lewisham Hospital were "taking the NHS into new ground" and were "dangerous" given the pressure on A&E services.
"When we were in Government we did close some A&Es because sometimes it makes sense to do that, you can save more lives by centralising services on one particular site, every locality cannot necessarily sustain an A&E," he said.
"However what is different about Lewisham is that this A&E is being closed purely on cost grounds.
"To solve financial problems in one trust, the Government are saying they are going to take away the successful A&E department of another. That is taking the NHS into completely new ground.
"I think it is dangerous to do that, given the pressure that we seeing on A&E in London and right across the country."