The Health and Safety Executive (HSE) has carried out an unannounced inspection at Northern Ireland aerospace company Thompson Aero Seating.
It's understood staff at the Chinese-owned aeroplane seat manufacturer in Portadown complained about health and safety on the site after three workers went off sick with Covid-19.
One worker claimed that staff in one division were less than two metres apart while carrying out their work.
The HSE has begun visiting workplaces after receiving complaints about almost 500 employers during the coronavirus lockdown. A spokesman for the HSE said: "We can confirm that an unannounced inspection was carried out at Thompson Aero Seating today (Thursday). We are unable to provide any further information at this time."
It's understood that with around three members of the team off sick with Covid-19, colleagues had requested furlough leave as members of their family were vulnerable.
But they claimed that they had only been offered sick pay - which is paid at a lower rate than the government's furlough scheme. However, the furlough scheme only applies where companies have no work for employees to do as a result of the pandemic.
DUP Upper Bann MP Carla Lockhart said she had been contacted by concerned staff at the company, which has remained open through lockdown.
She said: "Thompson Aero need to listen to their employees and make sure they are safe in the workplace.
"I've already contacted the Health and Safety Executive to urgently review Thompson Aero and take action if needed."
A spokeswoman for Thompson Aero said: "Three employees of Thompson Aero Seating have recently tested positive for Covid-19 and are currently self-isolating.
"Our thoughts are with them as we wish them a full and speedy recovery.
"Thompson Aero Seating is following all government guidelines as well as those from the Health and Safety Executive.
"We continue to communicate closely with employees and are implementing all measures to protect our people including the provision of personal protection equipment (PPE) and additional deep cleaning at our sites.
"The health and wellbeing of our people is our priority at all times."
However, the company would not comment on the outcome of the inspection.
Ulster Unionist Party MLA Doug Beattie said he had also been contacted by constituents who were concerned at conditions in the factory.
He said the company had continued to operate during the lockdown, unlike others, who had opted to close.
However, all manufacturers have been permitted to stay open throughout lockdown, provided they maintain social distancing.
Mr Beattie said: "They have said they'd had to stay open because the companies they supply - like Airbus and Boeing - would just go elsewhere if Thompson didn't keep supplying them.
"But that doesn't stop the fact that if staff are concerned about social distancing and protection, the company is going to have to take measures."
Trade union Unite also has a representative in the company but said it would not be commenting.
The company paid off around 350 contract workers back in March.