Barco, 19, has impressed for the Argentinian club and the Seagulls have reportedly held talks with his representatives as they prepare transfer package for the next window which opens in January.
Brentford – who are seeking a new left back following an injury to Rico Henry – are also keen, along with Newcastle, Chelsea. Wolves and Man City.
Boca Juniors however are not prepared to let their prize assesst depart easily and are said to be preparing a new contract to help fend off interest.
Barco is said to have a release clause of around £8m, which Brighton are prepared to match, and he is contracted with Juniors until December 2024.
Boca board member Marcelo Delgado, as reported by www.90min.com, said the club are looking at a new deal – despite the interest.
"Barco has a contract with us," he said speaking with D Sports Radio. "At the moment, we have not received any proposal for him. We are thinking about improving the contract for Valentin."