Which regular expression use to replace on all occurrences found in a file in Eclipse?

Well, I have a CSS file of more than a thousand lines, where for every class there listed, there is a code @external declaring the same, eg:

@external agora-eu-posso-usar-minha-classe;
.agora-eu-posso-usar-minha-classe{
    /* CSS... */
}

The fact is that I discovered that if I give a @external * at the beginning of the code, it already assimilates all CSS classes and I do not need to declare one by one.

Well, with the problem solved, my code has now become full of @external [...] and I would like to replace all those lines with Regular Expression.

What expression would return everything within @external [...] ; ?

Points to consider:

• The [...] can contain any valid CSS class name;
• The [...] can contain several declared classes, eg @external classe-1, classe-2;

What I'm trying (no, I have no knowledge in regex) is more or less this:

($@external+\w+\(\))