ASOS "totally refutes" claims from a workers union it is risking employees' safety by not enforcing social distancing measures during the coronavirus outbreak.
GMB union accused ASOS of "playing Russian roulette with people's lives".
ASOS told Radio 1 Newsbeat this has "created panic and hysteria in an already uncertain time" about working conditions in its Barnsley warehouse.
The site employs up to 3,500 people, of which 500 can be on-site at any time.
The union had carried out a survey which suggested the majority of staff felt unsafe at work as they were working too close to one another.
The site is a distribution centre for the online clothing store and is on the list of government exemptions that can stay open during the current shop closures.
One ASOS employee told Newsbeat they were "frightened for their families as well as themselves" because workers in the warehouse aren't able to keep two metres apart, as instructed by the government's social-distancing measures.
'Additional health and safety measures'
'Mike', who didn't want to give his real name, worries that people are at risk.
"They don't want to be taking the virus home and passing it on," he says.
But in statement an ASOS spokesperson rejected claims that staff are unsafe.
"Since the lockdown, we have introduced a range of additional health and safety measures and the Environmental Health Officer, who visited the site on Friday, confirmed he was happy with the protocols we have in place," it says in a statement.
The government says that businesses and workplaces should encourage their employees to work at home, wherever possible, and has advised people to stay two metres away from other people at all times during the coronavirus outbreak.
"Trying to stay two metres, it's really hard, because working patterns haven't been changed to protect workers," Mike says.
"When workers are packing items it's only about three feet, if that, away from each other, and they're full everyday.
"So it's 150 packers all working on stations next to each other."
Mike's also concerned that the virus could spread easily among his colleagues because of how they clock-in at the beginning of a shift.
"You might have 50 people all queuing up at turnstiles trying to get into the warehouse to start work," he adds.
Asos has denied this. It's told Newsbeat it has 90 packers, 3.8 metres away from each other - and that every other packing line has been removed.
It adds: "Marshals (team leaders, health & safety staff and union reps) are there to manage safe flow and implement social distancing as best they can. Shifts are finishing up early to allow staggering of people as they leave the site.
"We've also made changes to the turnstiles. Our indoor turnstiles are permanently open to avoid bottle-necking.
"Employees have to take personal responsibility for following all available guidance, however."
The GMB union has been encouraging people to sign an open letter to ASOS CEO Nick Beighton to improve the situation.
Barnsley Council has also visited the site and said that ASOS is complying with social distancing measures.
On a site visit last Friday the council said "at no point did our officer see any member of staff not in compliance with this".
It is not known when ASOS introduced its new safety measures.
The new social distancing measures came into practice on Monday 24 March.
Dipo Osikoya, an employment lawyer at Harcus Parker says there is help for people who are worried about their health and safety in the workplace.
"If you are worried about being forced to go to work, or you're worried that your employer is not doing enough to protect your health remember that there is relevant legislation in place," he tells Newsbeat.
"The Health and Safety at Work Act says that employers must ensure the safety, health and wellbeing of employees, casual workers and temps whilst at work. If you are a member of a union speak to a union rep or seek legal advice."