The British government should not ignore alleged human rights abuses in Qatar after the Middle Eastern state committed £5bn ($6.2bn) to the UK over the next five years, Amnesty International said on 27 March.
The warning from the UK branch of the human rights organisation follows the major announcement at the Qatar-UK Business Forum in London. The extra money will go towards technology, infrastructure and energy projects.
"Qatar's wealth rests partly on the systematic exploitation and abuse of hundreds of thousands of migrant workers from poor countries like Nepal and India," said Allan Hogarth, head of policy and government affairs for Amnesty International UK.
"Most of the stadiums and infrastructure for the 2022 World Cup are being built by migrant workers who are often forced to live in squalid accommodation while having their passports taken from them and their wages either withheld or only incompletely paid.
"We've been saying for a long time that ministers must guard against the temptation to avoid 'difficult' issues like human rights when big trade deals are on the table.
"Qatar's wealth may be behind some of the world's most dazzling infrastructure projects, but it shouldn't blind ministers to the human rights realities behind the country's glitzy façade."
Ali Sherif Al Emadi, the head of Qatar's sovereign wealth fund, said he was optimistic in Britain's post-EU future, while International Trade Secretary Liam Fox said the government looked on "in admiration" at Qatar's economic plans.
"Your 2030 National Vision is among the most ambitious plans of its kind in the world," he said.
The UK is looking on in admiration as you work tirelessly to expand your infrastructure, rebalance your economy, and nurture your country's human capital.
"Like the UK's Midlands Engine and Northern Powerhouse, Qatar is developing local economic capacity to meet the challenges of the future.
"Both Qatar and the UK know that such ambitions cannot be realised unilaterally.
"Both nations are looking for reliable international friendships, and seeking to build long-term, committed partnerships able to rise to meet these challenges."
The comments come just two days before the UK government invokes Article 50 of the Lisbon Treaty and triggers Brexit talks with the EU on Wednesday 29 March.