Myer announced on Friday it would temporarily close all stores for at least four weeks from Sunday, and stand down 10,000 staff without pay.

The SDA, the union for retail, fast food and warehouse workers, said the government had failed to step up.

Some 30,000 retail workers had already been stood down in the past week, the union said.

"Myer's decision makes the situation even more serious and urgent - this is a brand that has not only been a major employer, but a symbol of Australian retail success, for more than a century," SDA national secretary Gerard Dwyer said in a statement on Friday.

"How many more major and minor brands - retailers big and small - (will) take unilateral action because the government has left them no choice and the prime minister fails to extend to them what the community expects."

Prime Minister Scott Morrison said on Friday that details of the plan to effectively cocoon businesses will be announced in the next few days as part of a third stimulus package, which will also include commercial and residential rental assistance.

Mr Morrison said there were some businesses that would have to close their doors and the government wanted them to effectively go into hibernation for six months.

While its stores are shut, Myer will continue to operate all online business, and full and part time staff are being given greater flexibility to access annual leave and long service entitlements.

Myer chief executive John King said the outcome is "one of the toughest decisions this company has faced in its 120 years of operation".

The SDA, along with the Australian Retailers Association, reiterated a call for a multibillion dollar rescue package for the industry.

They are calling for wage subsidies, rent and debt relief and underwriting of credit.

However the government has repeatedly baulked at the idea of wage subsidies for workers.

Australian Associated Press