Coronavirus: £14m for firms to make 'million face masks' a week
Factories in south Wales and Lancashire have started making "high quality" face coverings as part of a push to produce a million a week.
Some £14m is being invested by the UK government, with productions underway in Port Talbot and Blackburn.
Face coverings are already compulsory in shops across Scotland, and will be in England from 24 July.
Masks are also compulsory on all public transport across the UK, including Wales from 27 July.
"This is a major step to ensure that this country can meet any increase in demand for face coverings by working with British firms to establish the capability, capacity and skills required to manufacture these items at scale," said Cabinet Office Minister Michael Gove.
"These production lines will be able to get millions of face coverings to the public, without putting any additional pressure on NHS supply chains."
The Cabinet Office said 10 production lines had been bought, including 34 tons of equipment and machinery, while a further 10 had been commissioned from Coventry-based automotive company Expert Tooling and Automation Ltd.
The mask will be disposable, single-use coverings.
Engineering firm British Rototherm Group at Margam, in Neath Port Talbot, has expanded its workforce to meet the new mask orders.
Cookson & Clegg in Blackburn has also begun manufacturing.
A third site at Transcal at Livingston in Scotland will be online in the coming weeks.
'Good news story'
Visiting the south Wales site on Monday, Welsh Secretary Simon Hart said the investment was good news for the company and for the UK.
"There aren't many good news stories coming out of Covid - this happens to be one of them," he told BBC Wales.
"This is about members of the public being properly equipped, not just now but also for any future similar occurrences, if that was ever to happen."
UK officials said the new production sites would ensure public demand for face coverings did not impact on the supply of higher-grade face masks for front-line NHS staff.