spatial point pattern with correlation structure

Dear all,

I was wondering if there is an easy way to generate coordinates of 
clustered spatial point pattern.(possibly with variations on the degree 
of aggregation).

So far one can easily generate random patterns (splancs: csr; sp: 
spsample) or regular (sp: spsample or some simple lines of programme), 
but I cannot find out if there is some existing function in R capable of 
generating some points clustering...

Any suggestion welcome,

Best,

Patrick