WRITERS visiting from abroad are “humiliated” by border and customs checks, the head of the Edinburgh Book Festival said today.

Nick Barley said one author had been told to supply his marriage certificate, his daughter's birth certificate and bank statements, before being sent for biometric testing.

The literary celebration is due to open on Saturday, but Mr Barley said they are still awaiting visas for four people scheduled to take part.

He told BBC Radio Scotland: “The stories I’m hearing from some of the authors from around the world are pretty devastating, I have to say.”

He said the writer whose daughter’s birth certificate was demanded “was so humiliated by that he decided he didn’t want to go through with the process of coming to Edinburgh to talk.”

However, Mr Barley said he had persuaded him “to stick with it and thankfully we got the visa.”

First Minister Nicola Sturgeon said it was “really not acceptable that one of the world's most renowned and respected book festivals is being undermined in this way.”

A Home Office spokesman said: "We welcome artists and musicians coming to the UK from non-EEA countries to perform.”