Another Sydney school has been shut for cleaning and contact tracing after a student tested positive to the coronavirus, the fourth school to do so in a week.

Tangara School for Girls in Cherrybrook is the latest to close, after a student was among the nine new cases of COVID-19 diagnosed in NSW in the 24 hours to 8pm on Friday.

Students and staff have been asked to self-isolate while contact tracing occurs.

Principal Rita Sakr has informed parents the school will be “non-operational” to accommodate thorough cleaning and tracing.

Earlier this week, Bonnyrigg High School and Greenway Park Public School were shut and students advised to self-isolate after three tested positive on Tuesday.

Another primary school in Sydney’s west, St Margaret Mary’s Primary School in Merrylands, was closed on Wednesday after a COVID-19 case was identified in that school community.

St Francis Xavier’s College in Hamilton East, Newcastle was also closed for cleaning this week after a student tested positive.

Authorities are still determining how the Tangara School for Girls student contracted the virus.

Among the other cases announced on Saturday are two overseas arrivals, four close contacts of other diagnosed COVID-19 cases and three cases which are still under investigation.

It comes as NSW residents became largely confined within their own state, after Queensland’s new border restrictions came into effect early on Saturday.

Queensland Premier Annastacia Palaszczuk has followed the lead of her counterparts in WA, SA, and Tasmania in barring all NSW residents as community transmission continues in the state.

Travel to Victoria is discouraged by the NSW government, leaving only the Northern Territory, which has barred Sydneysiders but is accepting travellers from some NSW regions.

Over half of the country’s population is now banned from entering Queensland, with ACT and Victoria also declared hotspots.

NSW is also ramping up its own travel restrictions.

From Friday, NSW residents returning from coronavirus-hit Victoria must now complete two weeks of hotel quarantine.

Entry to NSW from Victoria is now restricted to flights landing at Sydney Airport, except for border community residents with permits.

Those returning through the airport will be sent into 14 days of hotel quarantine at their own expense, alongside those returning from overseas.

-with AAP