The Euros start in just over a week’s time and England are among the favourites.
The 27-year-old Maddison was introduced as a 61st-minute substitute in Monday’s 3-0 friendly win against Bosnia and Herzegovina at St James’ Park.
But Maddison, whose form tailed off for Spurs following a strong start to the Premier League season, is among seven players who will not make Southgate’s final squad. The rest are yet to be named.
Maddison has won seven caps for his country but faced stiff competition for places, with England enjoying a glut of options in offensive positions.
England face Iceland in their final pre-tournament friendly at Wembley on Friday.
Southgate’s final 26-man selection is scheduled to be announced on Saturday.
England are in a group with Slovenia, Denmark and Serbia at the championships.
© Agence France-Presse
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