By Magdalena Mis

LONDON (Thomson Reuters Foundation) - Two Polish brothers were jailed under Britain's modern slavery laws for six years each on Monday for stealing wages of around 18 other Poles they tricked with promises of work in the UK, prosecutors said.

Erwin and Krystian Markowski were found guilty to charges of conspiracy to arrange travel with a view to exploitation and conspiracy to commit fraud by false representation between 2015 and 2016, the Crown Prosecution Service (CPS) said.

The Markowskis identified victims in their native Poland -- often jobless and in need of money -- and offered them travel, work and accommodation in Britain, it said.

The victims lived in squalid conditions in Nottingham, central England, and worked at the Sports Direct warehouse in nearby Derbyshire, the CPS said.

The brothers seized their travel documents, credit cards and most of their wages and -- by sometimes threatening violence -- exerted total control over them, the CPS said.

"The Markowskis preyed on vulnerable people in Poland and promised them accommodation and a tempting wage in order to lure them to the UK," Janine Smith, Chief Crown Prosecutor of CPS East Midlands, said in a statement.

"The reality upon arrival was a life of squalid living conditions and near total control by the defendants.

"Modern slavery is a global issue that often goes unseen, but prosecutors and police are determined to take all possible steps to hold those responsible to account."

In September, Prime Minister Theresa May pledged to use 33.5 million pounds ($41.8 million) from the foreign aid budget to focus on combating slavery in countries that are the source of proven trafficking routes to Britain.

There are an estimated 13,000 victims of forced labor, sexual exploitation and domestic servitude in Britain.

In 2015 Britain passed tough anti-slavery legislation introducing life sentences for traffickers and forcing companies to disclose what they are doing to make sure their supply chains are free from slavery.

Sports Direct was condemned by lawmakers last year for its treatment of workers, including paying some less than the minimum wage for shifts at its Derbyshire warehouse.

An independent report commissioned by the company found "serious shortcomings" in working practices, which it is taking steps to tackle.

In a statement on Monday Sports Direct said it welcomed the conviction and "will not tolerate these kinds of behavior", the BBC reported.

(Reporting by Magdalena Mis @magdalenamis1, editing by Ros Russell; Please credit the Thomson Reuters Foundation, the charitable arm of Thomson Reuters, that covers humanitarian news, women's rights, trafficking, property rights, climate change and resilience. Visit http://news.trust.org)