Pascal Gross was one of four Brighton players shown on video, along with Shane Duffy, Alireza Jahanbakhsh and Leandro Trossard
Brighton have launched an investigation after a video emerged of four players inhaling from balloons during the club's winter break in Spain.
Shane Duffy, Pascal Gross, Leandro Trossard and Alireza Jahanbakhsh were shown, although it is not known what - if anything - was in the balloons.
A club spokesperson said: "The club is aware of the video circulating on social media.
"This matter is being dealt with internally."
Brighton manager Graham Potter has taken his squad to Spain after a difficult run where they have taken four points from their past six games, leaving them just three points above the relegation zone.
Their next Premier League game is at Sheffield United on 22 February.
Source: bbc.com