The 19-year-old has caught the eye in recent weeks after setting up two goals on his England U20 debut against Italy during the international break.
English publication 'The Daily Mail' reports that interest in the player is at an all-time high, with Chelsea and Tottenham joining Southampton and a host of Championship sides in closely monitoring the youngster.
The young right-back has played just 13 games in League One since breaking into the MK Dons side and spent a brief spell on loan with Icelandic side Throttur Reykjavik last season.
Brittain started his career as a winger before being moved deeper but he still regularly looks to use his attacking instincts from full-back.
The youngster is out of contract next summer and both clubs are considering swooping for the player, though the 'Dons' would be due a development fee.