According to the Daily Mail, the plan would see £35million earmarked for eight African countries including Sudan which is ruled by accused war criminal President Omar Hassan al-Bashir.
In return, they would be asked to intercept refugees heading to the Mediterranean and beyond.
But the March meeting of 28 ambassadors, led by Germany, agreed that 'under no circumstances' should the public learn of the agreement.
An aide of EU High Representative for Foreign Affairs Federica Mogherini even warned that Europe's reputation was at stake if the details emerged, it was reported.
The minutes of the meeting and other classified documents were obtained by German publication Der Spiegel and public TV station ARD.
According to the report, the £35million would be used over three years to train border police and set up detention camps, mainly in Sudan.
Other measures include installing cameras, scanners and servers for registering refugees to the Sudanese regime.
But critics have attacked the plan for relying on a dictatorship accused of killing tens of thousands of people to now uphold the human rights of migrants.
Marina Peter, an expert on the Horn of Africa region at the German relief organisation Bread for the World, told Der Spiegel: 'A regime that destabilised the region and drove hundreds of thousands of people to flee is now supposed to stem the flow for the EU.'
|All roads lead to Europe: Sudan is key transit route for migrants fleeing countries such as Somalia, the Democratic Republic of Congo, Eritrea, Ethiopia and the Central African Republic|
Experts estimate at least 200,000 people have been killed, although the Sudanese government says only 10,000 have died.
A further 2.7 million people are estimated to have been uprooted by the conflict, which began when mostly non-Arab rebels took up arms against the government.
The ICC issued arrest warrants for Bashir in 2009 and 2010, but the Sudanese President rejects the court's authority and has regularly flouted the warrants.
Amnesty International has also accused the Sudanese secret service of torturing members of the opposition, while the United States claims the regime finances terrorism.
The German Ministry for Economic Co-operation and Development has confirmed the 'action plan' but says it has not yet been implemented.
The German development agency GIZ is expected to coordinate the project.
Sudan is key transit route for migrants fleeing countries such as Somalia, the Democratic Republic of Congo, Eritrea and the Central African Republic.
From there, they make their way to Libya where they attempt to boards boats across the Mediterranean into Europe.