A gathering on Mother's Day has infected nine people with coronavirus and affected three school year groups, a local business and child and adult care settings.
Some of the people linked to the gathering are understood to have since been admitted to hospital.
The Welsh Government said that the nine people infected were from four separate households.
A spokesman said: "A cluster of cases associated with a family event on Mother’s Day has been identified by Environmental Health teams in Newport.
"The Regional Incident Management Team has so far identified 9 cases from a possible 4 households linked to an outdoor gathering on Mother’s Day. Children who were at the event were isolated before their positive results were received together with their school bubbles.
"The positive cases associated with this gathering have so far impacted on 3 year groups in one school, a child care setting, a local business and an adult care setting."
On Friday morning, WalesOnline asked First Minister Mark Drakeford about the incident and whether he was aware of it.
"Yes," he said. "It is exactly the sort of thing IMT reports reflect on each day. That is where the TTP system is so useful, that is where that intelligence comes from."
The First Minister said this kind of very local example was not unusual.
He added: "Everyday more or less have accounts from the local teams and those really helpful.
"I became worried a couple of weeks ago about the facts that the figures in Powys were going up everyday that week. I was afraid we were seeing something happening there.
"But the report said that they were able to demonstrate that because the county had a relatively small population two or three outbreaks in workplace settings with half a dozen people falling ill, that each was enough to explain why those figures were heading that way.
"Sometimes they can trace an outbreak to a specific birthday or a Mother's Day party."
According to the latest Public Health Wales Figures, Blaenau Gwent and Monmouthshire have both seen a slight increase in the infection rate in the past 24 hours.
Conwy and Merthyr Tydfil (which currently has the highest infection rate in Wales at 127.6 per 100,000) have also seen an increase.
"In many areas of Wales, the numbers of cases are falling,” said Dr Eleri Davies, incident director for the novel coronavirus outbreak response at Public Health Wales, speaking on Thursday.
“It is now so important that we don’t throw away the substantial gains that we have made, and I would like to send a clear message to everyone that coronavirus hasn’t disappeared and there are still a large number of people who have not been vaccinated.
“In order to protect everyone, including the most vulnerable, we must all stick to the rules.
“Welsh Government restrictions state that you should not go into any other household or mix indoors with other people who you don’t live with.
“If you are contacted by your local TTP team then it is important that you are truthful with them about where you have been and who you have met. They are not there to judge, they are there to help prevent ongoing transmission of the virus and to protect the community.
“If you are asked to self-isolate by your local TTP team then please ensure that you do so for the full ten days – this will help break any chains of transmission.”
