Thousands of children have returned to Sydney's schools after nearly four months of home learning as Australia's largest city eased more restrictions just a week after lifting its Covid-19 lockdown amid a surge in vaccination levels.

A faster-than-expected vaccine uptake brought forward further lifting of restrictions by several days as New South Wales (NSW), home to Sydney, topped the 80 per cent double-dose immunisation rate over the weekend in people above 16, Reuters reported.

Masks will be off in offices, while more people can gather at homes and outdoors. Retail stores, pubs and gyms can allow more vaccinated patrons and nightclubs can reopen for seated drinking, while weddings can have unlimited guests.

Students in preschool and years 1 and 12 returned to the classroom, while all others will get back next week.