URGENT: Space char in rewriterule

I have the following rewriterule: RewriteRule ^(([0-9]|[A-Z]|[a-z]|_)+)$ redirect.php?$1 [L] that transforms http://mysite.com/XXX to http://mysite.com/redirect.php?XXX and I need to also include to space char, for example that transforms http://mysite.com/AB XX to http://mysite.com/redirect.php?AB XX I didn't find a way to write the " " characters. I tested with RewriteRule ^(([0-9]|[A-Z]|[a-z]|_| )+)$ redirect.php?$1 [L] but didn't work. Thanks! Rob