Hi Dave
I think Intasure may do group policies. I know a couple of people who have had a decent discount with them on 3+ apartments.
Best thing to do is email them for a quote on 1 apartment and when they ring you ask for a price for the number of properties you have, at least that way you will know how much the difference.
This is the Egypt page for a quote
Intasure - insurance that speaks your language
Cheers