Abstract. Let m, n be positive integers and p a prime. We denote by ν(G) an extension of the non-abelian tensor square G ⊗ G by G × G. We prove that if G is a residually finite group satisfying some non-trivial identity f ≡ 1 and for every x, y ∈ G there exists a p-power q = q(x, y) such that [x,′ is locally finite (Theorem A). Moreover, we show that if G is a residually finite group in which for every x, y ∈ G there exists a p-power q = q(x, y) dividing p m such that [x, y ϕ ] q is left n-Engel, then the non-abelian tensor square G ⊗ G is locally virtually nilpotent (Theorem B).