  We prove the following local version of Kakutani's characterization of
ellipsoids: Let $V$ be a finite-dimensional real vector space, $B\subset V$ a
convex body with 0 in its interior, and ${2\le k<\dim V}$ an integer. Suppose
that the body $B$ is contained in a cylinder based on the cross-section $B \cap
X$ for any $k$-plane $X$ from a connected open set of linear $k$-planes in $V$.
Then in the region of $V$ swept by these $k$-planes $B$ coincides with either
an ellipsoid, or a cylinder over an ellipsoid, or a cylinder over a
$k$-dimensional base.
  For $k=2$ and $k=3$ we obtain as a corollary a local solution to Banach's
isometric subspace problem: If all cross-sections of $B$ by $k$-planes from a
connected open set are linearly equivalent, then the same conclusion as above
holds.
