Downing Street says net immigration has fallen by a quarter since the general election
The Labour Party has become embroiled in a row with two of the UK's biggest retailers over claims they favoured East European workers over Britons.
Tesco and Next reject the claims, which had been due to be made by shadow immigration minister Chris Bryant in a speech that was leaked to newspapers.
In a wide-ranging speech later, he is expected to accuse the government of "gimmicks" on illegal immigration.
They include a van campaign with the message "go home", he will say.
In extracts from the speech published at the weekend, Mr Bryant claimed Tesco had moved a distribution centre to Kent where "a large percentage" of staff were "from Eastern bloc".
Staff at an original site, "most of them British, were told that they could only move to the new centre if they took a cut in pay", he was reportedly due to say.
But the supermarket giant said it was "wrong to accuse Tesco of this", saying it did not have such a distribution centre in Kent.
It said in a statement it worked "incredibly hard to recruit from the local area" and had just recruited 350 "local people" to its new distribution centre in Dagenham, east London.
The Home Office "go home" campaign is being investigated by the Advertising Standards Authority
In other extracts, Mr Bryant was reportedly expected to say: "Look at Next Plc, who last year brought 500 Polish workers to work in their South Elmsall [West Yorkshire] warehouse for their summer sale and another 300 this summer.
"They were recruited in Poland and charged £50 to find them accommodation.
"The advantage to Next? They get to avoid agency workers regulations, which apply after a candidate has been employed for over 12 weeks, so Polish temps end up considerably cheaper than the local workforce, which includes many former Next employees."
But a Next spokesman said the measure was not designed to get around the regulations, adding: "We are deeply disappointed Mr Bryant did not bother to check his facts with the company before releasing his speech.
"In fact, agency workers from Poland cost us exactly the same as local agency workers and our existing employees.
"The only reason we seek the help of people from Poland is that we simply can't recruit enough local people to satisfy these spikes in demand for temporary work."
Mr Bryant's speech is now expected to reflect subsequent discussions with Tesco and Next.
On Friday the Advertising Standards Authority (ASA) announced that it was investigating, following 60 complaints, a scheme which saw vans drive through London calling on illegal immigrants to "go home or face arrest".
A Home Office spokesman said it was in contact with the ASA and would "respond in due course".
In his speech, Mr Bryant is due to say that such "cheap and nasty gimmicks" by the government left "a nasty taste in the mouth".
"More interested in finding voters lost to UKIP than in removing illegal immigrants, they have resorted to gimmicks that have not impressed anyone," he will claim.
Mr Bryant will also propose new powers to tackle an "epidemic" of sham marriages, saying the way marriage law interacts with immigration is "not fit for purpose".
He will call for the Home Office to be given more information and powers to investigate suspicious marriages.
A Downing Street source said net immigration had fallen by a quarter since the general election and that Labour should apologise for having let immigration get out of control when in power.
Source: BBC News - Business http://www.bbc.co.uk/news/uk-politics-23662668#sa-ns_mchannel=rss&ns_source=PublicRSS20-sa
