Queensland will no longer offer hotel quarantine exemptions to diplomats after a coronavirus-infected contractor used the loophole to enter the state from Afghanistan.

Victorians trying to enter NSW have been issued a stern warning while health authorities work to track down and end the chains of COVID-19 transmission across the state.

Australia could face some food shortages due to Victoria's stage four coronavirus restrictions.

US President Donald Trump says he would approve of Microsoft or another major US company buying the US arm of the social media app TikTok, while continuing to threaten a ban if an acquisition deal is not reached by September 15.

Most retail in Melbourne will be closed to customers while tight restrictions will be in place at construction and meat processing sites, as part of efforts to slow the spread of coronavirus.

Microsoft Corp says it will push ahead with talks to acquire the US operations of Chinese-owned short-video app TikTok, a potential blockbuster deal that could reshape the social media industry and further inflame US-China relations.

Victoria's state of disaster declaration and Melbourne's hard lockdown will help secure the border with NSW and curb the spread of coronavirus into the state, Premier Gladys Berejiklian says.

STAGE FOUR BUSINESS CLOSURES AND CHANGES FOR MELBOURNEOPEN FOR ON-SITE WORK WITH COVID SAFE PLAN:* Supermarkets and grocery stores including liquor shops* Fuel retailers* Pharmacies* Post offices* Hardware, building an garden supplies for trade* Specialist stationery for business use* Maternity supplies* Motor vehicle parts for emergency repairs* Locksmiths* Laundry and...

A state of disaster has been declared in Victoria, with harsh COVID-19 restrictions on movement across Melbourne and an overnight curfew to be enforced by police.

LATEST DEVELOPMENTS* Another three Victorians and one NSW man have died, bringing the national death toll to 201.