Mortgage for expats without permanent residence

We are trying to secure a mortgage to purchase a new apartment in Belgium. We have already contacted 3 banks and all of them have said that they cannot start the application without a permanent residence card. Do you know any bank who are prepared to offer a mortgage to expats without permanent residence card? I read that any foreigner can buy property in Belgium but apparently the mortgages are limited to only permanent residents? Would really appreciate any help on this since we have already made an offer for an apartment and would like to proceed with the purchase at the earliest if mortgage is available. We have also completed 5 years in Belgium and already applied for our D cards 2 months back; however we still have to wait for another 3 months for the decision on the same.