Deloitte said jobs will be lost at Jarvis's head office in York and other sites including Doncaster, Glasgow, Leeds, Newcastle and Peterborough after three Jarvis companies went into administration last week.
It said: "After reviewing the business, and conducting negotiations with key stakeholders, the administrators have concluded that it is not possible to continue to trade the businesses in the absence of further funding.
"It has regrettably, therefore, been necessary to make some 1,100 redundancies across the three companies today."
Deloitte added: "Jarvis Accommodation Services Limited, the facilities management part of the group, continues to trade as normal.
"The administrators are working closely with all stakeholders to continue a normal level of service why they seek a buyer for the business as a going concern. The administrators have already received a significant amount of interest in this company."
Union leaders called on the Government to launch a "last-ditch" rescue package to save the jobs and claimed that Network Rail had failed to give assurances about Jarvis contracts continuing.
Bob Crow, general secretary of the Rail Maritime and Transport union, said: "The total cost of the administrators' Jarvis rescue package would be 19 million, money that would be easily recouped by the Government and Network Rail. That plan has been thrown out with callous disregard for the livelihoods of the Jarvis workforce.
"Instead, as a result of the Government refusing to use its legal powers to intervene and ignoring the administrators' proposals, over 1,000 workers will be sacked and their pensions destroyed. That is a scandal.
"There is still time to act. We have written to the Prime Minister and Secretary of State for Transport to ask them to use the Government's legal powers to intervene to protect the Jarvis rail workers. They cannot sit back and watch while these jobs are wiped out."
Gerry Doherty, general secretary of the Transport Salaried Staffs Association, said: "Yet again, the pain brought about by the cuts programme being pursued by Network Rail is felt by rail workers, many of whom have dedicated their working lives to the rail industry and are now being cast aside like rag dolls by children too old to use them.
"The Government should have long since intervened to stop Network Rail from laying waste to our rail industry. Unfortunately they haven't and nothing has been done to safeguard any of the jobs or skills lost.
"The absolute disinterest shown by Network Rail to the plight faced by Jarvis, their workers and their families and the loss of key engineering skills to the rail industry has been shameful, but no doubt it will be well rewarded when Network Rail directors dip their snouts in the trough for their annual bonus feast in a few months' time."