Sixty prisoners are "actively involved" in the disturbance at HMP Ranby after twice as many inmates refused to return to their cells, the Prison Officers' Association (POA) has said.
At around 12.30pm 120 prisoners refused to return to their cells. They have taken control of a unit.
We have got national resources at the prison trying to establish a surrender plan. We know 60 prisoners have been actively involved.
Mr Travis said today's disturbance was "no surprise" to the POA.
It's all down to chronic staff shortfalls and a management that are hell-bent on delivering things they can't deliver safely.
Prisoners are saying 'We're not dealing with this'. They will react.
More top news
Lottie and her dog Marley confronted a man who had taken a laptop and goods from a Lush store in Oxford.
Feeling colder with a biting, bitter windchill
A thoughtful teenager has taken Valentine's romance to a whole new level by buying 900 flowers and giving one to every girl in his school.