“Paged comments” and duplicated content !

Hello …

I am trying to remove some urls from my wordpress blog.

These urls created as a result of installing “paged comments” plugin.

The urls looks as:

————————————-
http://www.example.com/?p=400&cp=1

(using the default permanent links)
————————————-

I blocked this type of urls by robots.txt:

—————–
Disallow: /*cp=
—————–

It looks google still indexing new urls like above.

When trying to remove these urls by Goolge Webmaster Tools i get Denied.

Any explanations?

How to block these danger urls ?

Thanking you in advance.