"Instead of us being out there and being desperate to have an hour with him on his birthday he should be home with us.
"We're grateful to be seeing him but it still hurts."
Michael is serving a 15-year jail term for an attack on a Bulgarian barman in the Golden Sands resort, despite another man confessing to the assault. An appeal against the sentence is expected to begin on October 18.
Mr Shields added that his son is trying to learn Spanish and Bulgarian in prison.
He said: "Mike is just trying to keep his brain ticking over.
"I spoke to him yesterday and he sounded down but he perked up when he found out we had got the visit."
* REDS star Jamie Carragher will take part in an autograph signing session to help the Michael Shields campaign.
He will sign his name for £1 a time at Pryor's the jewellers on London Road, Liverpool, from 3pm on Thursday, September 29.
