Sydney has reported its worst day of the Covid-19 pandemic with five deaths and a record rise in locally acquired infections as a weeks-long hard lockdown is struggling to contain the highly contagious Delta strain of the coronavirus, reports Reuters.

Four of the five people that died were unvaccinated while one had at least one dose, New South Wales state health authorities said, as they implored residents to get inoculated as early as possible.

"Please now is the time to strongly consider getting vaccinated ... and for the elderly who have not been vaccinated, again, I put out a plea to you — make an appointment," New South Wales Chief Health Officer Kerry Chant told reporters in Sydney, the state capital and Australia's largest city.

Authorities also announced a one-week lockdown from today (Thursday) evening in a region north of Sydney, home to the state's second-largest city of Newcastle, after reporting new cases and finding fragments of the virus in the sewerage there.

There are 259 new Covid-19 cases in Sydney, out of 262 in all of New South Wales, health authorities have said.