Prof Neil Ferguson said that the Omicron variant of coronaviruses appears to be doubling every two to three days and that it could be necessary to impose new lockdowns.
Omicron is likely to be the dominant strain in the UK before Christmas, according to Ferguson, a member of the UK government's Scientific Advisory Group for Emergencies.
Ferguson said that it was likely to overtake Delta before Christmas.
Overall case numbers are still only 2% of all cases, but within a week or two, we will start seeing an impact on overall case numbers.
He said that case numbers were high in London and Scotland. Most of our foreign visitors come to London. He speculated that it could be linked to the Cop26 summit in Glasgow, as it had spread more quickly in Scotland.
