Almost 500 employees at a factory in Cornwall have now been tested for coronavirus after a single alert to the Track and Trace service identified more than 170 cases - many of which had no symptoms.

Cornwall Council has given an update on the outbreak at the Pilgrim's Pride Ltd food factory in Pool, where earlier this month it was confirmed that there had been "a small number of confirmed cases of Covid-19".

It has now said that it was a single alert to council's Public Health team from the national Test and Trace service that resulted in more than 170 cases of people who were unaware that they had Covid-19 and were not displaying symptoms.

In total, almost 500 employees at the factory have now been tested and the council said the "vast majority of the cases" who tested positive were not displaying symptoms.

The council said: "Swift identification of the initial case has therefore helped to limit the transmission of Covid-19 in the local community.

"All employees who have tested positive are isolating in line with government guidelines, as are those found to have been in close contact with them."

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Cornwall’s public health team provided the update at a meeting of the Covid-19 Local Outbreak Engagement Board yesterday and outlined the intensive testing they are carrying out to help limit the transmission of the virus, working closely with the factory, Public Health England South West and the NHS.

The council added: "The public health team provides an enhanced contract tracing service where they contact the individual identified to us by NHS Test and Trace and interview them about their recent activities.

"In this case the individual revealed to us that they worked at the factory, and so further investigations were carried out and testing procedures put in place."

The information on cases of coronavirus in Cornwall is updated weekly and can be found www.cornwall.gov.uk/coviddata

The data shows a sharp rise in cases in Cornwall over the last two weeks, the majority of which can be attributed to this outbreak said the council.

The most recent update on the website, yesterday, showed there had been been 1,361 cases in Cornwall and the Isles of Scilly up to that point, with 147 cases in the last seven days.

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Julian German, leader of Cornwall Council said: “This case demonstrates how the strategy of proactive testing is helping us to take action quickly to limit the spread of Covid in our communities.

"The council’s public health team review the situation daily and if any additional actions are needed the team stands ready to put them in place quickly."

Rachel Wigglesworth, interim director for public health for Cornwall Council, said: “We’ve quickly identified and tested hundreds of people, and in finding people who weren’t displaying symptoms we have potentially stopped much wider spread in our communities.

"We continue to closely monitor the situation and appreciate the cooperation of Pilgrim’s Pride Ltd. and their employees.

A representative from Pilgrim’s Pride Ltd said: "These are the first positive cases we have experienced at our site in Redruth since the outbreak of Covid-19 in the UK and appear to coincide with the outbreaks seen more widely around the county.

"To put this into context, we have seen significantly more cases of Covid-19 in Cornwall over the past 14 days than we have experienced within our business of 6,000 employees located in 13 sites across the UK - including Manchester, West Midlands and Leicestershire - since the onset of this pandemic.

“We recognise our role and responsibilities within our community and continue to follow and exceed government guidelines as we have been since March when Covid-19 restrictions were introduced.

"We have also implemented additional measures where they bring benefit to particular situations. We audit our own compliance of all Covid-19 controls daily.

“From the outset we have worked conscientiously to do all we can to protect our workforce and the local community. Our teams have been working extremely hard in collaboration with the local authority and public health to manage this challenging situation, and have bravely conducted themselves with professionalism and integrity as they continue to play their important role in maintaining the UK food supply chain.”