The Carter administration is considering asking Congress for authority to impose tight controls on hospital construction and expansion as part of a plan to limit rising hospital expenditures, according to informed sources.

The proposal, which is expected to be sent to Congress late this month, would also include a limit - tentatively in hospital revennues over those earned in a base year, probably 1976.

The administration's hospital cost containment program is widely viewed as the first step toward national health insurance.

Under the administration's tentative plan, controls would begin with a national quota for new hospital construction and expansion. A formula still to be devised would then allocate funds among the states for distribution to hospitals in a manner not yet determined, sources said.

Outlays for construction and expansion - about $5 billion last year - are generally viewed as crucial to limiting hospital operating costs, which have been going up about 15 per cent a year. Health economists estimate that every capital outlay dollar adds between 50 cents and a dollar to annual operating costs.

Hospital bills accounted for roughly 40 per cent of the $139.3 billion. Americans spent on medical care in fiscal 1976.

The administration's contemplated lid of 8 to 9 per cent on hospital revenue increases would be administered by the new Health Care Financing Administration in the Department of Health, Education and Welfare. The lid would include the inflation factor in the general economy [WORD ILLEGIBLE] about 9 per cent a year.

The legislation cal for enforcement by a "class of purchaser" approach, using [WORD ILLEGIBLE] bills such as Medicine, Blue [WORD ILLEGIBLE] other insurance companied. Roughly 90 per cent of today's hospital bills are paid by either public of private health insurance.

Four states that already have programs to contain increases in hospital cost - Massachusetts, Washington, Connecticut and Maryland - could be exempt from th federal controls if they met federal standards.

Among the issues still not resolved is whether non-supervisory workers' wages will be exempt from controls.The AFL-CIO already has told HEW officials that controlling the wages of workers under its jurisdiction would not be acceptable.

In announcing the administration's intention to curb hospital cost on Feb. 22, HEW Secretary Joseph A. Califano said "the voracious appetite of health care costs" had to be restrained "before it consumes whatever dividends there are from social economic policy."

The average daily cost of staying in a hospital - which generally takes into account room, board, basic services and use of the operating room - has increased form about $15 in 1950 to $175 in 1976.

According to a report by the Council on Wage and Price Stability, 75 per cent of this increase results from hospitals doing more - hiring more workers, providing more services and buying more materials - and th rest from raising prices.

"With insurance now paying approximately 90 per cent of all hospital costs, there is a strong incentive for patients and their physicians to seek the 'best possible care' almost without concern about its cost," the report said.