Nacional president Enrique Sánchez has confirmed that bids are already coming in for the 18-year-old centre-back, with an unnamed European club said to have made a serious approach that could develop into a formal offer.
According to La Tribuna, Coronel's rise since breaking into Nacional's first team has marked him out as one of Paraguay's leading young prospects, prompting growing interest from Europe. Sánchez said the contact so far has come through intermediaries rather than official channels.
"There are unofficial offers for Mauro Coronel; I received calls from Europe, from very serious people," the club president said.
Brighton are among the clubs reported to be tracking his progress. The Seagulls already have Paraguay international Diego Gómez on their books, a connection La Tribuna suggests has "raised expectations" locally about a potential move, though there is no indication Brighton are among those who have actually made contact. Nacional are understood to view Coronel as a player of considerable potential, with the club keen for him to continue accumulating first-team minutes and experience before any sale, in the belief that further exposure will only strengthen his case for a move to Europe.
Should Brighton move for Coronel, it would fit a familiar pattern for the club, who have built a reputation for identifying South American talent early and, in several cases, signing players before loaning them back to continue their development in familiar surroundings.
That approach has previously paid off for the Seagulls, and represents one obvious route should their interest in Coronel firm up into anything more concrete.
Coronel has emerged this year as a regular fixture in Nacional's back line in the Paraguayan Primera División, and has been talked up as a future member of the national team setup given his performances at club level.
Nacional, one of Paraguay's most successful clubs domestically, have a long history of developing players who go on to earn moves to Europe or South America's bigger leagues, and Sánchez's comments suggest the club expects Coronel's situation to develop further in the coming months as more suitors make themselves known.