Be careful here. The English and the Dutch verbs and verb tenses do not exactly correspond.
The best translation of "The clothes have been washed" is "De kleren zijn gewassen". By "best translation" I mean that in a situation in which an English speaker would say (for example, to his mother) "The clothes have been washed", a Dutch speaker in the same have situation would say "De kleren zijn gewassen".
For example, if your mother says to you "Why don't you go wash the clothes", most English speakers would reply "The clothes have been washed". Most English speakers would NOT usually reply "The clothes are washed".
On the other hand, if an English speaker says "The clothes are being washed" or "The clothes are washed every Saturday", a Dutch speaker would use "worden gewassen" rather than "zijn gewassen".