Queen Elizabeth Hospital in Woolwich says there is "no truth" in an online rumour that a patient has been diagnosed with the deadly Ebola virus.
Campaigner Ian Puddick appears to have started the rumour when he tweeted over the weekend: "1st London victim of EBOLA is a man from Sierra Leone secretly diagnosed a few days ago at QE2 Hospital Woolwich now at UCH."
The claim quickly spread online but a spokesman for the Lewisham and Greenwich NHS Trust, which runs Queen Elizabeth, denied there was any substance to it.
He said: "We haven't had any confirmed cases here whatsoever."
Public Health England announced last night there were no reported cases of Ebola in the UK.
An estimated 1,145 people across west Africa have died since an outbreak began in February this year.