Verstappen and Leclerc set for back of grid starts in Belgian Grand Prix
The governing FIA said both drivers had exceeded their allowed use of engine components, triggering the automatic penalties.
McLaren's Lando Norris (22), Alfa Romeo's Valtteri Bottas (32) and Alpine's Esteban Ocon (25) will also have grid drops for the same reasons while Haas driver Mick Schumacher (23) has a 10-place penalty.
The penalties will boost the chances of Mercedes's seven times champion Lewis Hamilton (37) and teammate George Russell (24) taking a first win of the season.
Ferrari's Carlos Sainz and Red Bull's Sergio Perez will also fancy their chances with their teammates likely to start far behind them.
Verstappen leads closest rival Leclerc by a mighty 80 points after 13 of 22 races.
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