  We study the central part of Lambda N and Lambda Lambda potential by
considering the correlated and uncorrelated two-meson exchange besides the
omega exchange contribution. The correlated two-meson is evaluated in a chiral
unitary approach. We find that a short range repulsion is generated by the
correlated two-meson potential which also produces an attraction in the
intermediate distance region. The uncorrelated two-meson exchange produces a
sizeable attraction in all cases which is counterbalanced by omega exchange
contribution.
