Separately harmonic functions, a Terada type theorem

Given D a domain in R-M, G an open set in R-N and E a subset of D verifying the harmonic analogue of 'Local Polynomial Condition of Leja' at some point in D. We prove that if f(x, y) is a complex function defined on D x G such that f(x, .) is harmonic on G for every fixed x is an element of E, f(., y) is harmonic on D for every fixed y is an element of G, then f is harmonic in (x, y) on D x G.