Dozens of workers at burger chain Byron have been arrested in raids by immigration officials.
The Home Office said 35 people from Albania, Brazil, Nepal and Egypt were arrested at restaurants across London.
The raids on 4 July were "intelligence-led" and were carried out with Byron's "full co-operation", it said.
The Home Office said Byron had done the correct "right to work" checks on recruits, but it was suspected the employees had provided false documents.
A Home Office spokesman dismissed reports that a training event had been set up to lure workers to a location where they would be arrested.
He said officers had carried out "visits to a number of Byron Hamburgers restaurants across London".
The burger chain, which has 65 outlets across the UK and over 1,500 employees, said the Home Office recognised Byron was "fully compliant with immigration and asylum law in its employment practices".
As a result, the chain would not face any legal action itself, the Home Office confirmed.
Byron said immigration officials removed members of staff suspected of "not having the right to work in the UK, and of possessing fraudulent personal and right to work documentation that is in breach of immigration and employment regulation".
"We have co-operated fully and acted upon the Home Office's requests throughout the course of the investigations leading to this action, and will continue to do so," it added.
But the story prompted the hashtag #boycottbyron to trend on Twitter, where there was both criticism and support for the company.
Twitter user @abbiewastaken wrote: "Luring your own staff who's labour you've benefited from for 4+ years into a room filled with cops is next level SNAKE. #BoycottByron".
Others were in support of the chain. Twitter user @alrightlandlord said: "The people were here illegally, so no, I won't #boycottbyron".
Byron was founded in London in 2007 by Tom Byng, who developed the idea for the company while living in New York.
The chain was previously owned by Gondola Group, which also owns the restaurant chains Ask, Pizza Express and Zizzi but it was sold to Hutton Collins Partners in October 2013 for £100m.