Transport company Martin Transport is currently under fire over the deaths of six people on its London-to-Brisbane journey.
A court has ordered an investigation into the deaths, which happened in January and February.
The company said the deaths were caused by “poor ventilation” and had taken place at its depot in Stockport, south-east London.
Martin Transport said in a statement: “We are conducting an internal investigation into this tragic incident to establish whether any staff members acted inappropriately, and are undertaking further inquiries to ensure the safety of all our customers and employees.”
Martin Transport has previously said it does not comment on ongoing investigations. “
Our thoughts are with the families and friends of the victims.”
Martin Transport has previously said it does not comment on ongoing investigations.
In February, the company said that it was conducting a review of its procedures following the deaths.
The inquiry will focus on the company’s “continued commitment to transparency and accountability”.
Transport for England is investigating the deaths but said that no final conclusions had been reached.
The coroner’s report will say how the deaths unfolded.
Martin said that its operations in Stockton and Stockport had “always been an exemplary place for our staff to work”.
The company is one of the biggest companies in the world, with about 50,000 employees and a turnover of about £3.7 billion ($5.6 billion).