Tamworth will lock down for a week after "somebody left Newcastle" to visit the town.

NSW Premier Gladys Berejiklian said that there were no confirmed cases in Tamworth yet but several exposure sites with links to the Hunter's outbreak.

"Unfortunately somebody from Newcastle went to Tamworth and there are a number of exposure sites there," she said.

Dr Kerry Chant said a young lady was exposed to the virus in the Hunter, travelling to Tamworth on August 4 and visiting a number of venues.

On Sunday, a third case tested positive in Armidale.

Anyone who attended the following Tamworth venues on the specific dates and times identified by public health officials are considered close contacts and must get tested and isolate for two weeks and await further advice from NSW Health:

Anyone who attended the following venues on the specified dates and times are considered casual contacts unless they have been contacted by NSW Health as close contacts, and must get tested and isolate until a negative test result is received:

More exposure sites may be announced as public health investigations continue.

It comes as popular Tamworth restaurant The Pig and Tinder Box's management announced it would close for the foreseeable future after news came to light that a positive COVID-19 case had attended the venue briefly on Thursday, August 5.

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Meanwhile, contact tracers are closing in on a link between a beach party at Blacksmiths Beach and a growing COVID-19 cluster at the University of Newcastle.

The number of positive cases in the Hunter grew to 17 on Sunday with the addition of six new cases.

By Sunday evening there were also reports that positive cases had occurred at Newcastle Basketball Stadium and the Williamtown RAAF base.

Sunday's new cases were among 262 new locally acquired infections reported across the state. Seventy two of the individuals were in the community while infected.

A male young adult and a male in his 20s linked to the Blacksmiths Beach party and a female young adult and a male in his 20s linked to the University of Newcastle made up four of the Hunter's new cases.

"There seems to be a tenuous link between that (university) cluster and a party at Blacksmiths Beach, which Sydneysiders attended. We have now confirmed the link with the Sydney visitors," Public Health physician David Durrheim said on Sunday.

International House and Oval Number 2 at the Callaghan Campus have been listed as sites of concern.

Hunter New England Health said any student who is a resident of International House or who was at International House between Wednesday 28 July and Saturday 7 August is considered a close contact.

The order only applies to residents of International House or those who were there during the specified times, not other students on campus.

Anyone who attended Oval Number 2 between 5:30-6:42pm on August 4 is considered a casual contact.

In an update to staff and students, University of Newcastle Vice Chancellor Alex Zelinsky said the affected students were receiving care from Hunter New England Health and the university.

"We understand that the situation on Callaghan Campus is upsetting and we also appreciate those of you who have sent messages of support to our impacted students living on Callaghan campus," he said.

"If you have not been to the above venues of concern during the specified time periods, then continue to observe the relevant health orders in place for where you are living right now."

A female student from Morisset High School was also among the new cases.

The infection source for the sixth case, a man in his 30s from Raymond Terrace, remains under investigation.

"We have some idea where the link may be but that is not completely solved yet," Dr Durrheim said.

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