Multilevel pseudo maximum likelihood

Dear all,

I am interested in an application of linear multilevel model with unequal
selection probabilities at both levels.
Do you know if there is an R function for multilevel pseudo-maximum
likelihood estimation? Or is it possible to obtain these estimates using
the nlme package? In practice what I need is to insert in  the likelihood
the individual and cluster level design weights.

Thanks in advance,
Caterina