More than 8.4million workers are now registered on the government's furlough scheme, up from eight million a week earlier, the Treasury has said.
The total number of claims has risen to £15billion as ministers warn of plans to close the scheme to new applicants in July.
The Job Retentions Scheme was first phased in around eight weeks ago, after thousands of businesses were forced to shut following a lockdown on the country.
It allows employers to claim support to pay their staff - equivalent to 80% of their monthly salary up to £2,500.
Chancellor Rishi Sunak has confirmed that the scheme will continue until October, but the government will ask companies to "start sharing" the cost of the scheme from August.
This could involve asking companies to cover up to 30% of wages, which would then be subsidised by the government to avoid a "cliff edge" cut off.
Under new terms being drafted up, employers will be allowed to take furloughed workers back part-time, and all firms using the coronavirus job retention scheme will be required to make the payments, even if they remain closed.
A Treasury source said: "We’ve got two full months of support left and afterwards the government will help to pay people’s wages, but it’s fair to everyone that businesses contribute as they get back to work."
Elsewhere, the Chancellor is also said to be in talks to close the scheme to new applicants at the end of July, according to The Financial Times.
All high street businesses were ordered to close on March 23 after the UK went into lockdown following a surge in coronavirus cases.
Employees across the UK were told to work from home where possible, leading employers who were facing significant losses to apply for help via the Chancellor's salary scheme.
Boris Johnson says those who are unable to work from home can now travel - though they should avoid public transport where possible.
This will be followed by schools, car showrooms and open markets reopening on June 1 and non-essential businesses, like retail outlets, will open their doors from June 15 as lockdown measures are further eased.
Speaking in the House of Commons earlier in May, Rishi Sunak said: "Until the end of July there will be no changes whatsoever. Then from August to October, the scheme will continue for all sectors and regions of the UK but with greater flexibility to support the transition back to work.
"Employers currently using the scheme will be able to bring furloughed employees back part-time. And we will ask employers to start sharing with the government the cost of paying people’s salaries.
"Full details will follow by the end of May, but I want to assure people today of one thing that won’t change: workers will through the combined efforts of Government and employers continue to receive the same level of overall support as they do now at 80% of their current salary up to £2,500 a month."
