Access denied on adding item to SharePoint list using LINQ

Hello..

I'm using LINQ to insert an item to a SharePoint 2013 list, Customer. The list consist of a lookup field, Nationality .

The user have Contribute permission on the Customer list and Read only permission the Nationality lookup list.

On adding a new item I'm redirected to the AccessDenied.aspx page and System.Threading.Thread.AbortInternal() exception is thrown but the item gets added to the list.

I've also noticed that if I give the user Contribute permission on the lookup list (Nationality) the issue disappears.

Please guide me on how to fix this issue

Thanks in advance