Help with preg_replace

There is a string:
Code:
{{double_tag_skip}}

<skip_strip>before {block_tag_skip} after </skip_strip> 

{normal_tag_strip}
After parsing required:
Code:
{double_tag_skip}

<skip_strip>before {block_tag_skip} after </skip_strip>
Double {{ = {
Inside <skip_strip> = nothing
Strip the rest {blah}