  We define the Poisson quasi-Nijenhuis structures with background on Lie
algebroids and we prove that to any generalized complex structure on a Courant
algebroid which is the double of a Lie algebroid is associated such a
structure. We prove that any Lie algebroid with a Poisson quasi-Nijenhuis
structure with background constitutes, with its dual, a quasi-Lie bialgebroid.
We also prove that any pair $(\pi,\omega)$ of a Poisson bivector and a 2-form
induces a Poisson quasi-Nijenhuis structure with background and we observe that
particular cases correspond to already known compatibilities between $\pi$ and
$\omega$.
