Mid-Norfolk MP George Freeman has called for track and trace to be "done quickly" after a reported outbreak at Wayland prison.
Several cases of Covid-19 have been identified at HMP Wayland in Griston, near Watton.
With numbers not yet confirmed, Mr Freeman said it is vital that the outbreak is controlled.
He said: “The prison is a major local employer in the community and as we saw with the outbreaks last summer in local food factories, it’s vital that track and trace is done quickly.
“Thank you to the local Breckland Council staff for moving so fast.”
In the seven days leading up to March 23, 48 cases were recorded in the Wayland, Ellingham and Great Hockham area.
With a rate of 507.9 cases per 100,000 people, it had the fourth highest infection rate in the country.
Keith Gilbert, Breckland's councillor for Watton, said it would be a “great concern” if another large outbreak was announced.
He said: “Even if it is only among the prisoners, they are in contact with people who come and go and with people who work there - who then come out into the community.
“It is a concern, and for the prisoners themselves.”
Outbreaks are defined as there being two or more confirmed cases among individuals associated with the same non-residential setting.
The Ministry of Justice said its priority was to "limit the spread of the virus and protect the lives of those who live and work in prisons."
A spokesman added: “We have taken precautionary measures at Wayland, in line with public health guidance, and will continue to closely monitor the situation.”
Last year, a coronavirus outbreak also hit Norwich Prison, located on Knox Road.
Another Freedom of Information request revealed that since the beginning of the pandemic up to January 4, 195 inmates at the prison had tested positive for the virus, with an outbreak forcing the site into a mass testing regime in December.
At its peak, more than 100 prisoners were suffering from Covid-19, with 103 positive cases identified in the prison on Sunday, December 10.
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