Some 18 people at an office block in Greater Manchester have become infected with Covid-19.
The Oil Centre on Bury New Road, Heywood saw cases jump from five to 10 in two days from September 16 to September 18, Crown Oil Limited confirmed .
The number of positive cases at the centre, used by Crown Oil Limited employees and other businesses, now stands at 18, 17 of which are employed by Crown Oil.
A spokesperson for Crown Oil Limited said: "Across the four sites that make up the Bury operations of Crown Oil Limited, there have been some Covid-19 cases over the last two weeks, predominantly on one floor of one site, with one site having no cases and two others a single case.
"We have reduced the number of staff working on one site to reduce further the risk of transmission.
"The total number of cases within that building who are employed by Crown Oil Limited is currently 17 - those employed by other businesses currently amounts to one.
"Over a two-day period the numbers increased from five to 10. However, in the last four days we are not aware of any new cases and are hopeful that the spread of the virus from this incident has been contained."
Crown Oil Limited says Covid-secure processes have been implemented at the Bury New Road sites to ensure the safety of staff - including the cleaning of desks, one-way systems and screens around desks.
Most Read
The company says it was the subject of an unannounced visit from the Health and Safety Executive earlier this month, which confirmed measures were Covid-compliant.
The spokesperson added: "In line with government guidelines, screens have been fitted to desks prior to any infections which negates the requirement for the two-metre zone and we understood to be a more effective way to protect staff.
"We employ a one way system, sanitising facilities and full signage reminding staff of their obligations to themselves and others.
"Contact with staff from different floors and buildings is kept to a minimum, we have reduced the number of staff in the office and require those staff to wear face masks when moving around the office.
"In addition, cleaners are onsite each morning prior to staff entering the buildings, staff also clean their workstations every day and we have a rota to ensure all communal surfaces are cleaned throughout the day.
"Employees are provided with a copy of our risk assessment advising of all the measures and requirements we have put in place to ensure the workplace is Covid-secure - these risk assessments are regularly reviewed and updated in line with government advice.
"With regard to isolation and testing, we have always followed government guidance which clearly states that if you are not displaying any of the symptoms you are not required to either isolate or take a test.
Don’t miss
"We have and will continue to advise staff in line with the guidelines. There is often an element of panic in circumstances such as this.
"As a responsible employer and again following government guidelines we have advised staff only to take a test if they are showing one of the recognised symptoms.
"It is clear from the reports over the last few weeks that the testing system is being overwhelmed by individuals who do not have symptoms and we did not wish to add further strain to a limited resource by encouraging individuals to undertake tests outside of the guidelines.
"To be clear, at no time has any manger been instructed by the company to advise anyone either not to isolate or not to take a test if they are displaying any one of the published symptoms.
Don't miss a thing - sign up for your free North West newsletter - and follow us on LinkedIn
Email newsletters
BusinessLive is your home for business news from around the North West- and you can stay in touch with all the latest news from Greater Manchester, Liverpool City Region, Cheshire, Lancashire and Cumbria through our email alerts.
You can sign up to receive daily morning news bulletins from every region we cover and to weekly email bulletins covering key economic sectors from manufacturing to technology and enterprise. And we'll send out breaking news alerts for any stories we think you can't miss.
Visit our email preference centre to sign up to all the latest news from BusinessLive.
For all the latest stories, views, polls and more - and the news as it breaks - .
"Having consulted with the HR department, no employee has made such an allegation and we would encourage anyone who believes that to be the case to come forward so that we may carry out a full investigation."
Rochdale council has shown support for the company, saying: “We are looking into reports of positive cases at Crown Oil in Heywood.
“Our public health and public protection teams have met with Public Health England and the Health and Safety Executive to investigate this.
“We are very pleased with how engaged the company is in this process and how proactive they have been in seeking out support.”