Theatre critic Mark Shenton said a performance of musical Into the Woods was spoiled by involuntary noises made by a group of mentally-disabled people.

He has called for performances where such disruption is likely to be flagged up so others can choose whether to go.

But managers at Derby Playhouse said their shows were open to all and the idea was unworkable and unfair.

Do we then have a separate performance for the people who rustle their sweets? Or cough? Karen Hebden, Derby Playhouse

Mr Shenton said: "When we have a sign language interpreted performance these are advertised in advance and we know that is what it is.

"Going to this unwittingly, not realising what it is, we had no idea there would be a disruption.

"I think as long as we know in advance we could make a choice for ourselves whether we wanted to be there," he said.

Playhouse chief executive Karen Hebden said on the occasion in question, some of the group agreed to leave at the interval and serious disruption would always be dealt with.

However, she insisted audiences could not be segregated: "Do we then have a separate performance for the people who rustle their sweets? Or cough? Or don't fit into the seats because they are a little overweight.

"It's nonsense. It's like asking to have performances for children, which besides everything else would be impossible because so many young people come to our shows."

Michael Brookstein from disability rights group People First said: "If people do have a problem with any noise, the first people they should talk to are the support workers.

"It's vital that people with disabilities can experience theatre, both performing and watching, in a mixed environment, so they can show what they can do and what they can get out of it."