Redirect URL with fancy URL turned on

[Carlos]

But each block is actually a page that is included e.g. in sitemap. I don't want the content of that blocks to be visible as separate pages

Have you tried making those pages private? (won't be redirected, but not indexed nor visible)

but this seems not to work. What may be wrong?

What does it do? "Page not found"...?

Is your site at the root of the domain? (RewriteBase / in .htaccess)