display does not work for option elememt on IE

[b]style="display:none" does not work for option element
[/b]
Hello
I have a select list and I need a way to set certain option tags invisible. I tried applying style="display:none" to the option tags but this has had no effect.
The reason for this is that I am going to use some JavaScript to dynamically enable some selections in the drop down list.
Please see the attached code snippet.
Thanks

<select id="counties" tabindex="1">
 <option value="">Select</option>
 <option style="display:none" value="IE76176089">Carlow</option>
 <option style="display:none" value="IE96268862">Cavan</option>
 <option style="display:none" value="IE55624026">Clare</option>
 <option style="display:none" value="GB55624026">London</option>
 <option style="display:none" value="GB55624026">Surrey</option>
</select>