It is assur midirabbanan

to invite a non Jew for a yomtov meal, the reason that the Gemara states is that a Jew is not allowed to cook for a goy on yomtov, the exceptions are when the goy is not an important person, a house-aid or a cleaning lady can be invited on the assumption that one is not going to be embarrased if there isn't enough food.
I realised that in an environment where Jews and non Jews interact, due to certain events that happened on yomtov, I thought I'd mention this again in my almost hibernating blog!

Gmar Chasima Tova