We consider a bilevel continuous knapsack problem where the leader controls
the capacity of the knapsack and the follower's profits are uncertain. Adopting
the robust optimization approach and assuming that the follower's profits
belong to a given uncertainty set, our aim is to compute a worst case optimal
solution for the leader. We show that this problem can be solved in polynomial
time for both discrete and interval uncertainty. In the latter case, we make
use of an algorithm by Woeginger for a class of precedence constraint knapsack
problems.