A new variant of coronavirus has been identified in England and is spreading rapidly.
Matt Hancock, the UK Health Secretary, told British MPs:
"Over the last few days, thanks to our world-class genomic capability in the UK, we have identified a new variant of coronavirus which may be associated with the faster spread in the south of England."
He said the numbers of the new variant of coronavirus "are increasing rapidly".
He told the Commons: "Initial analysis suggests that this variant is growing faster than the existing variants.
"We've currently identified over 1000 cases with this variant predominantly in the south of England although cases have been identified in nearly 60 different local authority areas.
"And numbers are increasing rapidly."
The news came as he moved London into Tier 3 lockdown as cases spike.
Maria Van Kerkhove, the WHO's technical lead says there is "no evidence so far" that the new strain of Covid "behaves differently".
She said the variant was already been monitored by the Virus Evolution Working Group. "It's come up in the context of mink variants identified elsewhere."
Mike Ryan, WHO's director of emergencies, said the WHO had been made aware of the new variant by the UK authorities.
"Obviously we are looking at the significance of this. We've seen many variants and we've always said this virus evolves and changes over time and we've seen different variants emerge.
"The question is what is their significance in public health terms and certainly, looking at this particular variant it seems to have become more prevalent in the UK and we will obviously need our international lab network to see if that variant is becoming more prevalent on an international basis.
"But again I would like to say that these kinds of evolutions and mutations are quite common.
"The question we have, as we had most recently with the mink variants in Denmark and the previous variations of the virus - does this make the virus more serious, does it allow the virus to transmit more easily, does it in any way interfere with diagnostics, would it any way interfere with vaccine effectiveness?
"These are questions that we have and we have no information to suggest that any of that is the case."
He praised the UK authorities for releasing information on the variant saying it was the "height of transparency".