Australia’s second-largest city has begun a second lockdown in response to a spike in new coronavirus infections.

Five million Melbourne residents will be barred from leaving home for six weeks, except for essential reasons.

Police say they are setting up a “ring of steel” around the city, with “checkpoints anytime and anywhere” to enforce the measures.

Borders between Victoria, of which Melbourne is the capital, and neighbouring states closed on Tuesday.

Prime Minister Scott Morrison paid tribute to Melburnians’ resilience on Wednesday.

“The rest of the country knows that the sacrifice that you’re going through right now is not just for you and your own family, but it’s for the broader Australian community,” he said during a news conference.

Mr Morrison also said he was proposing measures to slow the return of Australian nationals from overseas.