LONDON — The fate of thousands of workers hung in the balance on Wednesday after the collapse of Carillion, a major construction and services company that has a vast network of subcontractors and reaches deep into many facets of British life.

Work has slowed on a range of Carillion projects, and some subcontractors, unsure if they will be paid or continue working, have begun curtailing assignments. The cracks appearing in Carillion’s sprawling network of services to the public and private sectors amplified fears that its failure could lead to the downfall of other companies that relied on it, putting tens of thousands of people out of work.

The demise of Carillion, which entered liquidation on Monday, poses a political as well as economic challenge to the Conservative government of Prime Minister Theresa May, which declined to bail out the company. Even after it became clear last year that the company was in trouble, the government continued to award Carillion major contracts.

“It looks like the government was handing Carillion public contracts either to keep the company afloat, which clearly hasn’t worked, or it was just deeply negligent of the crisis that was coming down the line,” Jeremy Corbyn, leader of the opposition Labour Party, said in Parliament on Wednesday.