The EU risks a confrontation with Donald Trump after it sought to stall the awarding of a lucrative Balkans pipeline contract to a company fronted by his personal lawyer, documents seen by the Guardian show.

Brussels has clashed with Trump over trade, Ukraine and military spending, but the intervention in the Southern Interconnection pipeline project appears to mark the first time it has challenged a commercial venture by those close to the president.

The pipeline will run through Bosnia and Herzegovina. Under what Bosnian sources say have been months of pressure from US officials, its leaders have been moving quickly to award the contract to a previously little-known company based in Wyoming.

AAFS Infrastructure and Energy was incorporated in November last year and has not disclosed its owners. It is fronted by two leading members of Trump’s campaign to overturn his 2020 election defeat: Jesse Binnall, a lawyer who defended him against allegations of inciting the Capitol riots after his defeat, and Joe Flynn, the brother of the president’s former national security adviser.

Despite lacking any apparent track record, AAFS is planning to invest $1.5bn in the pipeline and other Bosnian infrastructure projects, its local representative has said.