* Immigration a hot political topic in Britain
* Senior MP accuses Tesco and Next of shunning UK workers
* Retailers deny unethical or illegal practices
By Andrew Osborn
LONDON, Aug 11 Britain's opposition Labour party is to accuse supermarket giant Tesco and clothing retailer Next of turning away British workers where possible to exploit cheaper migrant labour.
In a speech that will drag the firms into a politically-charged immigration debate ahead of a 2015 election, senior Labour lawmaker and immigration spokesman Chris Bryant will accuse the companies on Monday of deliberately excluding British people.
"It is unfair that unscrupulous employers whose only interest seems to be finding labour as cheaply as possible, will recruit workers in large numbers in low wage countries in the EU, (and) bring them to the UK," Bryant will say, according to advance extracts of his speech.
Polls show immigration is one of the subjects that worries British voters the most and any perception that retailers are deliberately disadvantaging locals could damage Prime Minister David Cameron's Conservatives as well as the firms themselves.
Cameron is trying to stop an exodus of voters to the anti-immigration UK Independence Party before the 2015 vote.
Bryant will accuse Tesco of favouring workers from Eastern Europe over British ones and of relocating one of its distribution centres in a way that discouraged local employees to continue working for the firm.
He will also accuse Next of bussing in workers from Poland to skirt British labour laws that would make hiring comparable local workers more expensive.
Next said in a statement on Sunday it did hire Polish nationals to work in Britain at busy times, but said it did so because it couldn't find enough Britons to fill vacancies and that it was not doing anything unethical or illegal.
"Mr Bryant wrongly claims that Polish workers are used to save money. This is simply not true," it said. "We are deeply disappointed Mr Bryant did not bother to check his facts with the company before releasing his speech."
Tesco could not be reached, but a Tesco spokesman told The Sunday Telegraph newspaper it was wrong to accuse the supermarket giant and that it tried hard to recruit local people where possible.
Bryant's intervention comes as Labour's opinion poll lead over the Conservatives narrows and its leader Ed Miliband faces criticism from colleagues for what they see as a failure to communicate the party's policies clearly or strongly enough.
"We're not suggesting any law has been broken," a Labour source told Reuters. "Tesco and Next are anecdotal examples," the source added, saying the party wanted to spotlight the problem so it could be solved.
Separately, Labour cited research that showed Britain had seen one of the biggest falls in real wages of any EU country since 2010.