An outbreak of coronavirus at a Norfolk prison has seen around 100 inmates and staff test positive.
Dozens of Covid-19 cases have been reported at HMP Wayland in Griston, near Watton, in recent weeks.
The prison service remains guarded over the incident, stating its "priority was to limit the spread of the virus".
But on Thursday, Dr Louise Smith, Norfolk's director of public health, confirmed the number of Covid cases at the Category C men's prison was touching three figures.
She said: "We have been working with Wayland prison since early January.
"They have done extra testing and about 100 tests came back as positive - split about half and half between staff and inmates."
Latest figures show Griston and the surrounding area currently have the second-highest infection rate in the UK.
For the seven days up to January 28, the area of Wayland, Hockham and Ellingham had a rate of 1,142.9 Covid cases per 100,000 people.
It also had the joint-highest number of confirmed cases in the country for the same period, tied at 108 with Hatfield East in South Yorkshire.
The area's infection rate and number of cases for the week up to January 28 were even higher, standing at 1,185.2 and 112 respectively.
Staying tight-lipped on the situation at HMP Wayland, a spokesman for the prison service said: "Our priority is to limit the spread of the virus and protect the lives of those who live and work in our prisons.
"We have taken precautionary measures at Wayland, in line with public health guidance, and will continue to closely monitor the situation."
Meanwhile, Claire Bowes, county councillor for the Watton area, has slammed the Ministry of Justice's (MoJ) apparent lack of transparency.
"It isn't acceptable that the wider community has not been kept better abreast of the situation by a government department," she added.
"Communication of that knowledge could help save a life."
An outbreak is defined as when two or more people associated with the same non-residential premises test positive within 14 days.
In December the MoJ confirmed a Covid outbreak at HMP Norwich, but it was not revealed until January that more than a quarter of inmates and 70 staff had contracted the virus since mid-November.
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