The BBC reported that the blast was accidental, citing investigators. London Fire Brigade said the incident at the factory in south-east London involved a diesel compressor.
ADM was forced to evacuate and shut down the plant following the explosion.
Three people were injured in the blast.
The agribusiness giant issued a statement after the explosion:
“There was an explosion at around 9 am, June 19, 2020, at our oilseed crushing plant located in Erith.
“The explosion happened in the extraction area of the facility. Three contractors who were working outside, in an adjacent silo, suffered injuries and were taken to a local hospital.
“The safety and health of all our colleagues and the community where we operate is our top priority, the fire brigade worked onsite and extinguished the fire, the plant was fully evacuated and shut down.”
‘Injuries consistent with burns’
Police said the three men that were hurt in the blast "suffered injuries consistent with burns.”
ADM said, at this point, it does not know what caused the incident.
The UK’s Health and Safety Executive (HSE) said it has begun "initial inquiries" into how the workers were injured.
More than 400 workers at neighboring businesses, including warehouses belonging to retailers, Ocado and Tesco, were evacuated, added the BBC.
The Erith plant processes about 1m tons of rapeseed each year and produces about 385,00 tons of refined oil for food ingredients and biofuels. The meal produced from crushing operations is used as a feed ingredient by livestock producers across Britain, France and Ireland.
