An epidemiologist says it was inevitable for cases of the new Covid-19 variant to be detected in New Zealand.

So far six cases of the new strain have been picked up during routine testing.

All of them are in managed isolation.

Otago University's Professor Michael Baker told Tim Dower given how rapidly it's spreading through the UK, it was only a matter of time.

"The new cases are a bigger risk as people will be more infectious during flights and in managed isolation facilities."

From January 15, travellers coming into the country from the UK and US will have to return a negative Covid-19 result, 72 hours before they can get on a plane.

It comes as six cases of the new UK variant have been detected in managed isolation in this country.

Michael Baker says it will help to minimise the likelihood of another community outbreak.

"If a person tests positive,  they'll have to delay their travel.

"This will be an added incentive for those looking to come home to be more cautious."