Business leaders and trade unions have told Boris Johnson he risks spreading confusion by making employers decide when to bring back their staff to offices and other workplaces.

Warning that the prime minister was “passing the buck”, trades unions said more guidance and support was required to ensure a safe return to work from 1 August.

John Phillips, acting general secretary of the GMB trade union, said: “The prime minister has once again shown a failure of leadership in the face of this pandemic. Passing the responsibility of keeping the people safe to employers and local authorities is confusing and dangerous.”

Frances O’Grady, general secretary of the TUC, said reopening the economy was vital for protecting jobs in the long-run but that the return to work needed to be handled in a phased and safe way. “The government is passing the buck on this big decision to employers,” she said.

“Getting back to work safely requires a functioning NHS test and trace system. Yet progress on test and trace is still patchy, and the government is still refusing to support workers who have to self-isolate by raising statutory sick pay from just £95 per week to a rate people can live on,” she added.

As the British economy slumps into the deepest recession for 300 years business groups said a safe return to work was contingent on schools reopening, and the capacity of the public transport system and wider public services.

Adam Marshall, director general of the British Chambers of Commerce, said: “Companies, in discussion with their employees, will decide how and when to return to offices safely. To take those decisions, businesses need crystal-clear official guidance.”

Josh Hardie, deputy director general of the CBI, welcomed the change in tone from the government but said firms would not be able to make decisions overnight.

“Concern about infection is still high. The government’s announcements will not change that overnight, but changes in messaging on transport and further testing can lay a path to building confidence and helping those who want to come back to the office,” he said.

“Businesses will now be closely examining government guidance. Clarity and consistency must guard against confusion.”

Official figures show almost half of the working population in Britain worked from home in April during the first full month of lockdown. However, significant divisions have emerged between people who can and cannot work from home, with sharp differences split across incomes, gender, age, ethnic background, education and geography.

As many as 57% of workers living in London did some work from home, the highest proportion in the country, compared with as few as 35% in the West Midlands and 38% in Yorkshire and the Humber.

According to the Resolution Foundation, fewer than one in 10 of those in the bottom half of earners say they can work from home. Official figures show more than two-thirds of managers, directors and senior officials are working from home, compared with 16% of sales and customer service staff.

Early signs from businesses suggest that Johnson’s easing measures are not shifting back-to-work plans.

Retailers Marks & Spencer, Sainsbury’s, Tesco and John Lewis all said they currently had only a small number of staff working in their offices with most still working from home.

Sainsbury’s said it was still unlikely to bring the majority of office staff back for several monthswhile Marks & Spencer is trialling an app which should help manage the number of people in its head office by allowing staff to book a time slot to attend.

Some of Britain’s largest banks – among some of the biggest office-based employers in the country – said they did not plan to ask staff to return staff to work from next month.

The Guardian understands that RBS, which has about 50,000 of its 65,000 staff working from home, is sticking with guidance it issued in May, that the vast majority of its workers will continue to work remotely until at least September.

Only 400 staff in highly regulated roles, including from its investment bank, were asked to return in June. It will review its position this autumn.

Lloyds is similarly sticking to plans that mean roughly 50,000 of its 63,000 workers will not set foot in an office until at least September. Most of those unable to work from home are bank branch staff, who count as essential workers.

Barclays has about 70,000 of its 80,000 global workforce working from home. Most of those going in to work are branch staff, and only 700 have been asked to return to offices across the UK, US and India over July and August.

The insurance market Lloyd’s of London is not altering its plans either. It plans to reopen its famous underwriting room on 1 September at half capacity. It usually has 6,000 staff in the building, and 40 are due to return next week The building has been closed since March.