The Interstate Commerce Commission, the nation's oldest independent regulatory body, has told its 1,059 employes that many of them may lose their jobs next year if Congress does not approve more money to keep the commission in business.

A senior ICC official said the layoff notices went out last week, one month after Congress approved a drastically reduced $48 million budget for the commission. This official, who asked not to be identified by name, said 40 to 70 workers would be laid off, even if Congress approves an emergency request for an additional $4.5 million next year.

"We're in a crisis here and we have to have, at minimum, that $4.5 million," the official said. "Through the appropriation process, the Congress is killing us. It won't take many more cuts at us to do it."

If Congress does not approve the emergency funds, the official said, "We'll wind up with a staff so small we won't be able to do anything at all. We won't even be able to do critical types of work."

The layoffs will begin in January, the official said. The number will depend on how many workers leave voluntarily before then. He said several workers already had found other government jobs on learning of the layoffs.

The Office of Management and Budget has approved an emergency plan to give the ICC all of its money for the entire 1985 fiscal year immediately, instead of releasing the money every three months as usual. Also, the OMB will approve the commission's request for more funds, according to an official there. But this official added that Congress was unlikely to approve the entire $4.5 million request.

The embattled ICC, which once held a tight rein over rates and fares for railroads, trucks and interstate bus companies, lately has found itself with less and less to do because of deregulation in those industries. Calls for the commission's abolition have been mounting -- from a House Republican study group, from the conservative Heritage Foundation and in an internal OMB memorandum last March.

In June, a Senate committee slashed $12 million from the ICC's $60 million budget after senators became infuriated to learn that the commission had not scheduled regular public meetings since the late 1970s and that the commissioners rarely talked to each other.

House and Senate conferees approved the $48 million financing level the first week of October as part of the catchall money bill approved just before adjournment.

An aide at the Senate Appropriations Committee said no one mentioned at the time the possibility that the reduced budget would lead to such personnel reductions. The aide said that various means of savings at the ICC were discussed, including reducing travel for staff and commissioners and by abolishing certain offices.

The ICC official interviewed said the $48 million would support 860 positions, not the current 1,059. But he added that fewer than 860 could be kept on because, since the commission had started fiscal 1985 with 1,059 workers, technically it is overspending.

"If they give us zero, we got a crisis on our hands," the ICC official said. "At this point, it's really a dice game. We don't know what Congress will do."