CORRECTION: On February 13 Migration Watch UK published a report that stated Brexit 'could cause migration to rise by 100,000.'
Migration Watch UK later retracted the report, admitting there were mistakes in the calculations they used.
Migration Watch UK said in a statement: "There was an error in the calculations which was unfortunately overlooked at the final stages of preparation.
"We apologise for the error and will rectify it in the course of producing a revised version."
