Up to 17 workers at a Siemens plant in Hull have been suspended amid claims they left their shifts to watch England play in the World Cup.
Unite the Union said staff were allowed to watch the semi-final match against Croatia on site during their night shift on 11 July.
It is thought some went home to watch the game while others went to a pub.
Siemens confirmed the suspension and said it was investigating "potential breaches of health and safety rules".
Kelvin Mawer, Unite the Union regional officer, said: "As far as I know, they went back to work when the game finished.
"I understand they were tested for drugs and alcohol and were all clean."
He said staff were given permission by management to watch the game, but the specific details were unclear.
Health and safety
"We just need to know what permissions were granted and what the parameters were," said Mr Mawer.
"The workers were very excited to watch the game, as most of us were. I don't think there was any intention to break the rules."
In a statement, the engineering giant said: "Siemens Gamesa Renewable Energy can confirm that 14 employees have been suspended on full pay pending the outcome of investigations into potential breaches of health and safety rules.
"Three agency workers were released and their agency has applied its own policies to manage any allegations."