The officers and Parochial Church Council of St Anne’s Church, Lewes, have echoed concerns over the continued closure of the public lavatories in Western Road.
They said it is causing distress to the regular congregation and visitors to the historic church.
The venue is expected to be filled to capacity on Sunday evening for the Battles for Peace and Freedom concert.
St Anne’s has been working on plans since last year to have its own loos and a food preparation area in order to be more accessible to the wider community, but this project is many months away.
A spokesperson said that to lose use of the nearby Western Road facilities without warning and without a time scale for repair was very worrying.
They have been closed since the end of January due to an electrical fault which is making them unsafe. The roof is leaking, causing damage to internal walls and the total bill for repairs and reinstatment is inexcess of £16,000.
The St Anne’s spokesperson continued: “We feel that as representatives of this significant church we must urge Lewes District Council to look at not only this site but the two other public conveniences in the town and ask themselves ‘Do they reflect and satisfy the expectations and basic needs of the thousands of visitors every year to this historic county town?’
“With an ageing and increasing population we must retain, restore and maintain these vital services.”
The council has bowed to pressure with an interim arrangement where an accessible loo is being made isolated and available to the public from tomorrow (Saturday).