As medical authorities announce the ninth person in the UK to be infected with the new Omicron variant of the virus, one of the Government’s key advisors on the pandemic has speculated that “quite a lot more” cases will be detected this week.

Professor Neil Ferguson also said that the government should “keep all options on the table” as health chiefs and the Cabinet urgently plan how to deal with the new variant, which reportedly spreads faster than other mutations of Covid-19.

The third confirmed case of Omicron in England was of a person who has now left the UK but who visited central London during a trip here, the UK Health Security Agency said.

This morning health authorities announced a further six cases had been discovered in Scotland.

Prof Neil Ferguson said "it's likely we'll detect quite a lot more cases in the coming days" because of the number of flights to the UK from southern Africa, where the new variant is spreading.

Omicron has been detected in a number of other countries, including Belgium, Denmark, Germany, Italy, the Netherlands, Australia, Hong Kong, the Cech Republic and Israel.

Ten countries in southern Africa are now on the UK's travel red list, meaning that until further notice, any British or Irish residents arriving in the UK after recently visiting any of those countries will have to quarantine in an approved hotel for 10 days. Residents from the countries themselves will not be allowed into the UK until the red list status changes.

Prof Ferguson told Radio 4’s The World This Weekend: “I think there will be substantially more cases … We should expect to have been seeded with infection. Though I support the measures introduced, we would like to slow that as much as possible, and slow the risks of spread.”

Given Delta was still dominant in the UK, the true effects, if any would not be seen until early next year, Prof Ferguson said.

He added: “Even if we have had 100 or more cases seeded into the country and even if it’s going quite quickly it will take really until January for it to reach levels which are anywhere near the levels we’re getting from Delta at the moment, we’re getting 40,000 cases a day or so from Delta.

“That’s not to say we can be complacent. If we do see very rapid growth from Omicron, and that’s a big if at the moment, we have no guarantee we will, but if we do then undoubtedly I think the government would be wise to keep all options on the table in terms of how to respond to that.”