John Bercow has been accused of abandoning political neutrality after he suggested many Eastern European immigrants worked harder than British people.
During a visit to Romania last week the Speaker is reported to have also criticised the British press for its anti-migrant tone.
"I believe things should be controlled and monitored when it comes to migration – any state that wants to protect its own people should do this – but there are also great advantages," he said.
"I want to underline the fact that there has been an important wave of immigrants that came to Great Britain from new member states and in many cases they came with aptitudes and a commitment, an involvement we haven't always seen in our labour force."
The Daily Telegraph reports Bercow also attacked the “negative and discriminatory" attitude towards immigration in the media.
"A free media is a vital part of a democracy. But the media is not the government and it is not parliament. I am here as a friend of Romania and someone who sees the benefits of immigration," he said.
As Speaker of the House of Commons Bercow, who was a Tory MP, is required to stay politically neutral. Ukip leader Nigel Farage said it was "outrageous" that Bercow was "happy to overthrow the wisdom of ages and think it acceptable to comment on matters that are both highly political and deeply contentious".
"He is a disgrace to the office of Speaker. There are very good practical and constitutional reasons why the Speaker is neutral, reasons that he obviously believes are beneath his own august self image," he said.
However Philip Hollobone, the eurosceptic who has raised concerns about immigration, told the Daily Mail Bercow was entitled to his views.
"As Speaker of the House of Commons, it is absolutely right that if he is asked a question, he is able to answer it freely and honestly," he said.
Bercow's comments come as the government prepares to lift transition controls that would give Romanians and Bulgarians the same rights to live and work in the UK as any other EU citizen.
The Speaker's pro-immigration stance is another example of how he has shifted from the hard right of the Tory Party to a more centrist position during his time in parliament.
In a Romanian TV report broadcast during Bercow's visit, he tells a press conference: "I strongly dislike stereotypes or caricatures of the workers of the people of another country".