RegExp to strip HTML comments

preg_replace('/<!--(.*)-->/Uis', '', $html)

This PHP code will remove all html comment tags from the $html string.

Are you just trying to remove the comments? How about

s/<!--[^>]*-->//g

or the slightly better (suggested by the questioner himself):

<!--(.*?)-->

But remember, HTML is not regular, so using regular expressions to parse it will lead you into a world of hurt when somebody throws bizarre edge cases at it.