Bulk Add Users to Azure Active Directory User Group

Hi

Currently using Windows Azure Active Directory - Deploying a new Azure Application

Environment: 5,000 users - where a Windows 2008 R2 ADFS and Dirsync environment has been deployed.

1,000 users will access this application. 

There is no On-Premise or Azure Security Group which I can apply for managing access to the new Azure Application.

HR can export a list of users including the User Logon / UPN which will access the application

Question: Is there a way through powershell/etc... to bulk add these 1000 users into an Azure Security Group.

My understanding is that the On-Premise Security Groups cannot be nested into an Azure user group 

Many Thanks