Chief executive confirms company with contracts for prisons has filed for administration and its sites are closing

• Business live – latest updates

Thousands of jobs could be at risk and dozens of government construction projects paused as ISG, one of the UK’s largest contractors, filed for administration.

In the biggest collapse of a UK construction company since Carillion, the ISG chief executive, Zoe Price, confirmed in an email on Thursday that the company had filed for administration and shut down all of its sites.