  The Bose et al.-Marletto-Vedral (BMV) experiment [S. Bose et al., Phys. Rev.
Lett. 119, 240401 (2017); C. Marletto and V. Vedral, Phys. Rev. Lett. 119,
240402 (2017)] aims to prove that spacetime is nonclassical by observing
entanglement generated by gravity. However, local hidden variable theories
(LHVTs) can simulate the entangled correlations. We propose to extend the
entanglement generated by the BMV experiment to distant quantum particles in a
Bell experiment. Violating a Bell inequality would rule out LHVTs, providing a
stronger proof of the nonclassicality of spacetime than the BMV proposal.
