Matt Hancock said that 1,000 cases of the new variant had been found in the last month - predominantly in south-east England, but spread across 60 different local authorities.
The health secretary revealed that 'similar variants' had been found in other European countries in recent months, and told MPs that the government had informed the World Health Organisation (WHO) of its presence in England.
He said there was 'nothing to suggest' that the new coronavirus variant would fail to respond to COVID vaccines - and urged the public to be 'vigilant and follow the rules' to prevent spreading the virus.
The health secretary also announced that Greater London, the south and west of Essex and the south of Hertfordshire would move into Tier 3 from Tuesday night following increased cases of COVID-19 in those areas.
Speaking in the House of Commons this afternoon Mr Hancock said: 'Over the last few days we have identified a new variant of coronavirus, which may be associated with the faster spread of [the virus] in the south east of England. Initial analysis suggests that this variant is growing faster than the existing variants.
'We have currently identifed over 1,000 cases with this variant, predominantly in the south of England, although cases have been identifed in nearly 60 different local authority areas, and numbers are increasing rapidly.
'There is currently nothing to suggest that this new variant is more likely to cause serious disease, and the latest clinical advice is that it that is highly unlikely that this mutation would fail to respond to a vaccine.'
COVID-19 cases rising
Mr Hancock said the government was unsure if the ‘exponential rise’ in coronavirus cases across some parts of the country recently was down to the new variant, but stressed it was essential to control the disease.
Cases of the virus were revealed to be doubling around every seven days, with people ‘of all age groups’ now contracting the disease, including the over 60s.
The health secretary added: ‘We know from painful experience that more cases leads to more hospitalisations and the loss of more of our loved ones… we know that this doubling of cases will be mirrored in hospital admissions, and it only takes a few doublings for the NHS to be overwhelmed.
‘Our NHS is straining every sinew to cope with the pressures as they always do, but if cases continue to double even they will be overwhelmed. So we must act now to shift the curve, because when the virus is growing exponentially there is not a moment to spare.’
Those areas moving into Tier 3 restrictions will do so from the start of Wednesday in attempts to get the virus under control. It had been reported in national media this morning that London and parts of Essex would come under tighter restrictions following growing rates of infection.
A first wave of GP-led sites began administering vaccines to patients aged over 80 today, with 100 sites set to begin vaccination by tomorrow.