More than one-fourth of the people working for the federal government last year were outide experts and consultants, not included on normal federal payrolls a Senate subcommittee reported yesterday.

The government spent at least $906 million on the consultants, the report said. But many of the 178 agencies involved in the study are unable to tell the public how many consultants they hired, who they were o rhow much their services cost.

In a survey described as the most comprehensive study made of the government's use of consultants, a subcommittee headed by Sen. Lee Metcalf (D-Mont.) found there often are few controls of safeguards to regulate the use of outside experts or to find out what they do.

The Federal Energy Administration, long accused of featherbedding, and the Energy Research and Development Administration were found to hire consultants to do more of their work than any other agencies. ERDA hired the equivalent of 110.200 fulltime employees as consultants in 1976. This equaled 13 consultants for every agency employee. The FEA, a relatively small agency, shelled out $20 million on consultants for the year.

The Small Business Administration hired the equivalent of 782 full-time employees as consultants, the Nuclear Regulatory Commission 600, the Geological Survey 301, and the Bureau of Prisons 177.

The study found that a host of little-known agencies spent one-third or more of their budgets hiring outside experts to do their work, often without competitive hiding. The Office of Territoria Affairs in the Interior Department, for instance, spent 2 per cent more on consultants than it did on full-time staff. Other big consultants users were the Pennsylvania Avenue Development Corp., the Nuclear Regulatory Commission, the Council on Environmental Quality and the National Endowment of the Arts.

A summary of the study by Library of Congress analyst Sharon S. Gressle stated: "There is ample opportunity for misuse of the [consultant] system. Allegations have been made that employees in agencies line up contracts for a given organization and then leave government service to go to work for the same organization.

"One must assume that there is a good deal of overlap. Conceivably a contractor may be doing similar studies for multiple agencies. Many agencies are seemingly unaware of studies being conducted for offices within their agencies."

In calling for tighter controls on consultants, the study noted it is often impossible to find out which consultants also are lobbyists with interests in conflictwith the government.