A new COVID-19 sub-variant has been detected in Victorian wastewater as virus case numbers across the country remain stubbornly high.

More than 30,000 new infections were reported along with a further 27 virus-related deaths on Saturday morning, with data still to come for South Australia, Western Australia and Tasmania.

This follows almost 47,000 cases and 34 fatalities reported nationally on Friday.

Meanwhile, Victorian authorities are monitoring the new BA.4 or BA.5 Omicron variant after samples were confirmed in a Tullamarine catchment, north of Melbourne.

The sub-variant has been recently detected in a small number of COVID-19 cases in South Africa, Botswana, Belgium, Denmark, the UK and Germany.

The World Health Organisation says there are currently no known significant epidemiological differences between the new Omicron strain and the more dominant BA.2 strain.

"There is no cause for alarm with the emergence of the new sub-variants," WHO regional director for Africa Dr Matshidiso Moeti said this week in a statement.

"We are not yet observing a major spike in cases, hospitalisations or deaths."

LATEST 24-HOUR COVID-19 DATA FROM ACROSS AUSTRALIA:

NSW: 13,601 cases, 18 deaths, 1491 in hospital, 72 in ICU

Victoria: 9559 cases, eight deaths, 403 in hospital, 21 in ICU

Northern Territory: 391 cases, no deaths, 28 in hospital, none in ICU

Tasmania: 1334 cases, no deaths, 48 in hospital, one in ICU

Queensland: 5878, one death, 538 in hospital, 22 in ICU