An Ethiopian farmer could sue the UK government after claiming a project that received funding from Britain led to human rights abuses.
The man - known as Mr O - told his British lawyers he was evicted from his farm, beaten and witnessed rapes as part of a "villagisation" scheme.
Mr O's lawyers say the programme receives funding from the UK Department for International Development (Dfid).
Dfid said it does not fund "any commune projects" in the country.
Ethiopia is among the biggest recipients of UK aid and in July 2011 received £38m ($61m) during the country's worse drought in a decade.
The UK government is also one of the main partners in Ethiopia's Protection of Basic Services programme, money from which lawyers for Mr O claim is helping to finance forced resettlement.
'Men were beaten'
Mr O - whose identity has not been revealed - lived in the Gambella region, which is one of four areas in Ethiopia subject to villagisation. About 1.5 million people are being resettled.
The married farmer, who has six children, told lawyers at London firm Leigh Day & Co his family were forced from their farm in Novermber 2011 by soldiers from the Ethiopian National Defence Force (ENDF).
His lawyers said he claimed that "several men were beaten, women were raped and some people disappeared" during the resettlement.
They added that Mr O's family were made to resettle in a new village where they were given no replacement farmland, food or water and could not earn enough money to live.
When he tried to return to his former home, he claimed he was hit repeatedly with a rifle butt and taken to a military camp by ENDF soldiers, then gagged and subjected to further beating.
The firm - who were approached directly by Mr O - wrote to the new International Development Secretary Justine Greening on Wednesday, asking for the release of several documents and further information about the role of Dfid in the villagisation process.
Lawyers are seeking to establish how far the UK government has gone to ensure British aid has not been used to contribute to human rights violations during the programme.
Rosa Curling, from the Leigh Day & Co team representing Mr O, said the government has "a responsibility for transparency".
"The UK spends a considerable amount of money on international aid and Dfid has a responsibility to ensure that this money does not contribute in any way to human rights abuses such as the ones suffered by our client.
"Our government has a duty to ensure that the programmes it supports meet the highest compliance standards," she added.
A spokesperson from Dfid said the threat of legal action meant they could not comment at length, but insisted the UK "does not fund any commune projects in Ethiopia".
The department has 14 days to respond to the letter. Depending upon the outcome, lawyers could demand disclosure of the documents from the courts.
Mr O is currently a refugee in Kenya, while his family remains in Ethiopia.