Each club is looking to strengthen their respective squads heading into the second half of the season as they prepare to fight for survival in the Premier League.
According to the Daily Star, Blas is one player that both teams are in negotiations to sign this month, although they do face competition across Europe, with interest from Lille and some Bundesliga outfits.
The Frenchman is typically an inverted right winger, and he has found the back of the net eight times already this season for Nantes.
Blas was also involved in the Under-19 European Championship tournament in 2016, being named in the team of the tournament as France went on to win the competition.
Newcastle and Watford face each other today in a crucial Premier League fixture at the bottom of the table. body check tags ::