Australia's most populous state of New South Wales has expanded its Covid-19 lockdown to the rural town of Tamworth due to concerns the coronavirus may have spread from Sydney into the countryside, Reuters reports.

State Premier Gladys Berejiklian announced the lockdown of the farming town after people known to have Covid-19 travelled from Sydney to Tamworth, about 414 kilometres to the northwest, without authorisation.

"As a precaution, the health experts have recommended we lock down Tamworth for one week," Berejiklian told reporters in Sydney.