ereg_replace help?

[Anon]

Hello everyone,
I have a problem.

I am trying to delete and url's from a $string.

$string = eregi_replace("http://[_.0-9a-z-].+([a-z]{2,3}$)","",$tag);
that is my regexp, but it only seems to work if there is no space after the url.
ie
"string http://www.url.com"
but url's aren't erased if the string is like

"string http://www.url.com more stuff"

any help?

Thanks