Leaders of two House subcommittees yesterday accused the Reagan administration of endangering drivers by scrapping a proposal to increase federal safety monitoring of the nation's trucking industry.

The now-defunct administration plan would have moved the Bureau of Motor Carrier Safety from the Federal Highway Administration to the National Highway Traffic Safety Administration, where, the plan's supporters say, BMCS would have been given more enforcement muscle.

BMCS's mission is to reduce the risk of accidents and deaths involving commercial vehicles, mostly big trucks with gross vehicle weights above 60,000 pounds. The FHA also has a safety duty, but the agency's primary concern is highway construction. The NHTSA's obligation is to enforce federal safety regulations affecting the development, design and manufacture of vehicles sold in the United States. All three agencies are under the jurisdiction of the Department of Transportation.

The Reagan administration last year asked Congress to approve legislation that would move BMCS to the NHTSA. Congress failed to act on that bill, largely because of dissension over the proposal within White House circles, Capitol Hill sources said yesterday.

The bill also was opposed by many companies in the trucking industry, which annually hauls about 75 percent of the nation's freight over interstate highways and state-maintained roads.

Reagan administration officials yesterday told a joint panel of House subcommittees overseeing consumer protection and transportation that they will not resubmit the transfer bill. Instead, the administration is reorganizing BMCS within the Federal Highway Administration, the administration officials said.

The problem with the adminstration's new plan is that many of BMCS's current problems stem from its location within FHA, said Rep. Cardiss Collins (D-Ill.), chairwoman of the subcommittee on government activities and transportation, and Rep. Timothy E. Wirth (D-Colo.), chairman of the subcommittee on telecommunications, consumer protection and finance.

Both Collins and Wirth said that BMCS, as presently constituted, is too understaffed and underfunded to monitor safety compliance by the trucking industry. The agency has 280 employes operating on a $14 million budget for fiscal 1985.

Of the 280 BMCS employes, 94 are inspectors assigned to check the safety practices of 225,000 trucking companies that own and operate a total of 3.5 million vehicles. Wirth said the mismatch of inspectors to carriers possibly contributed to an accident last August in which a truck, laden with deactivated torpedoes, overturned on Interstate 25 near Denver.

No one was killed in the accident, which tied up traffic in and out of the city for about nine hours.

"The driver failed to follow federal routing regulations that prohibit driving hazardous cargo through heavily populated areas," Wirth said. He said there is no record that BMCS fined or otherwise disciplined the trucking company, Riss International Corp. of Kansas City, Mo., for the alleged violation.

Riss officals reached yesterday refused to comment.

"It would be a grave mistake if the administration were to look to the Federal Highway reorganization as the final remedy to cure the longstanding ills that have hamstrung the effectiveness" of BMCS, Wirth said.

Federal Highway Administrator Ray A. Barnhart agreed with Wirth's and Collins' charges that the BMCS has not been effective in fulfilling its mandate. "When you say that we have not been doing our job as effectively as it ought to be done, I will endorse that statement," Barnhart said.

But he said that the safety bureau's problems could be corrected faster by dealing with the agency in its present position instead of transferring it to the NHTSA. "We have many capable and dedicated people in our bureau staff, all of whom are concerned primarily with seeing that our highways are free of unsafe commercial vehicles and operators," Barnhart said.