  By including an additional self-dual three-form we construct a Lorentz
invariant lagrangian for the abelian (2,0) tensor supermultiplet. The extra
three-form is a supersymmetry singlet and decouples from the (2,0) tensor
supermultiplet. We also present an interacting non-abelian generalization which
reproduces the equations of motion of [arXiv:1007.2982 [hep-th]] and can
describe some aspects of two interacting M5-branes.
