Families of inmates at Lewes Prison have condemned a new visiting system which they say makes it more difficult to see their loved ones.
Prisoners have also vowed to take action if changes are not made and a petition is being organised.
The previous system was more flexible, with families able to book shorter but more frequent visits, sometimes every day.
Now, visits must be booked in advance and last at least one and a half hours.
Some friends and family members say they are having to wait more than a fortnight for an appointment.
One relative said: "The system is simply appalling. The switchboard is constantly jammed and visits have to be booked a week in advance.
"Visits are snapped up like gold dust."
The Prison Service has admitted the new system, introduced by Governor Paul Carroll, has led to a reduction in visiting sessions.
A spokeswoman said: "There has been a reorganisation of visiting sessions which has involved some reduction on the number of visiting times.
"The Governor will always look at organising a visit in cases of particular hardship, where it may not have been possible to arrange a visit in advance"
But Tony Greenstein, of the Brighton Unemployed, Advice and Rights Centre, which is backing the families, said: "These are absurd and petty restrictions.
"Their only effect is to needlessly antagonise prisoners.
"It seems they have only been introduced for administrative convenience. Some people are being offered visits in three weeks' time.
"Only one third of remand prisoners eventually serve prison sentences. To punish these people in this way is to court trouble."
Senior governors at the jail say the system is better because it allows for at least one long visit a week and makes prison visiting more economical.
Chairwoman of the Board of Visitors Jane King said: "Prisoners said they preferred fewer and longer visits. There was no point in some families coming a long way for short visits.
"I think the problem has arisen because they are between sixty and seventy extra prisoners at Lewes at the moment and the demand for visits has increased.
"Everybody has the same opportunity to book a visit but some people have been booking ahead."
Lewes MP Norman Baker said he is writing to the Governor to establish the facts.
The changes coincide with new rules which ban the handing over of CDs or mini disc players to prisoners at visiting times. Items now have to be sent in by post.
It is felt the ban will reduce the flow of drugs and sharp objects into the prison.
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