Leigh Day, which was cleared of wrongdoing over lawyers’ pursuit of torture and murder claims against British troops in the Iraq War, said they had no knowledge of the poster until it was brought to their attention.
The firm said it does not represent any victims of the fire and that an internal investigation is under way.
A spokesman said: “Leigh Day have no prior knowledge of the posters displayed around the Grenfell Tower brought to our attention by The Times newspaper.
“As soon as the posters were brought to our attention, a full internal investigation was commenced under formal protocols. The two individuals concerned have been suspended whilst this investigation takes place.
“Leigh Day would never have given authority for the posters or their display and we are taking this matter extremely seriously.”
The Times said the poster was headlined “Free Legal Support”, featured British passports and gave an email address for the two paralegals which was different from their work contact details.
According to the newspaper, the poster said: “Our aim is to help you kick-start any potential insurance claims and review any complex documents.”
The paper reported that it also said: “We do not charge for the assistance we provide. However a third party may charge for their services.”