Multiple circular holes with owin function in spatastat

Dear sig-geoers,

       It's possible to making a multiple circular holes with owin() 
function in spatstat package if the circles are created in a loop 
function, for example:

##
##Circle x coordinates
x<-c(524237,524237,524237,524237,524237,524237,524237,524237,524242
,524242,524242,524247,524247,524247,524247,524247,524247,524247
,524247,524257,524257,524257,524257,524257,524257,524257)
##Circle x coordinates
y<-c(7978856,7978866,7978876,7978896,7978916,7978936,7978946,7978956,7978956,7978946
,7978936,7978956,7978946,7978936,7978916,7978896,7978876,7978866
,7978856,7978856,7978876,7978896,7978906,7978916,7978936,7978956)
##

CIR<-NULL
points(a1.past.syn[,1],a1.past.syn[,2])
   for (i in 1:length(x)){
   circle<-disc(radius=5,centre = c(x[i],y[i]))
   CIR<-rbind(CIR, c(circle))
}

Because I don't know, if I can use CIR's objet in the owin(poly = ... ) 
function, that uses list() for create this kind of object.

Thanks,

Alexandre dos Santos
Engenheiro Florestal, Dr.
Universidade Federal de Lavras
Departamento de Entomologia
Laborat?rio de Entomologia Florestal
Caixa Postal 3037
37200-000 - Lavras/MG
Fone: +55 (35) 9223-0304