Quinn Industrial Holdings (QIH) has said two of its directors were assaulted in a shop in Co Cavan on Friday afternoon.
In a statement, the company said the two men required medical attention following the incident.
They said the attacker fled the scene after staff and members of the public intervened.
QIH chief executive Liam McCaffrey said: “We are very grateful to members of the local community and to QIH staff who intervened so quickly to stop this vicious physical assault on two of our senior management team as they as they bought their lunch in a local store.
“Cowardly unprovoked attacks of this nature cannot be allowed to go unpunished and we trust the authorities will deal with this accordingly.”
Gardaí said they were “investigating an assault which occurred at approximately 1.30pm today in Ballyconnell”.
“Two males received facial injuries, which are not believed to be serious. No arrests have been made and investigations are ongoing.”
There has been a series of acts of intimidation and attacks on the property of senior management at QIH in recent years.
Last October, there was an arson attack at the home of Tony Lunney, a senior manager at the company.
A car owned by his adult daughter was set on fire outside the family home in Ballyconnell, Co Cavan.
There was also a suspected arson attack at the Cavan home of Dara O’Reilly, chief financial officer of QIH and another arson attack at a tyre factory owned by the family of another senior QIH manager last year.
The company was formerly owned by businessman Seán Quinn, though he lost control of it and the rest of his business empire during the economic crash.
Mr Quinn has previously condemned the attacks and has said he does not support them.