Thousands of construction industry jobs are at risk as ISG, a construction group that builds prisons and police stations, faces imminent collapse.
Sky News has learnt that Whitehall officials are lining up City advisers to work on contingency plans for ISG, which is expected to formally appoint administrators on Friday.
EY is on standby to handle the insolvency proceedings.
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Construction industry sources said that government officials were closely monitoring the crisis at ISG, which is expected to be the biggest casualty in the sector since Carillion collapsed in 2018.
ISG employs about 2400 people and counts Apple, Barclays and Google among its private sector clients in the UK.
It is also understood to be involved in construction projects for leading City law firms including Addleshaw Goddard.
One insider said that EY would be appointed as administrator to eight ISG entities, including ISG Central Services and ISG Interior Services.
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The accountancy firm is said to have been scrambling to find a buyer for the company after a South African bidder pulled out of talks several days ago.
ISG is owned by Cathexis, a Texan-based investor.
EY and the Cabinet Office declined to comment.