Railroad labor, apparently stung by criticism of its court victory overturning mandatory drug testing of employees involved in accidents, took the offensive and blasted the Federal Railroad Administration's safety efforts.

A panel of three Railway Labor Executives' Association officials told a press briefing Wednesday that while the FRA has been beating the drum for drug testing, it has clouded a much deeper problem . . . , a problem with its own lax, ineffective enforcement of existing rail safety laws.James J. Kennedy, the association's executive secretary, said that figures obtained from the government show that for the almost 315,000 violations uncovered by FRA inspectors on U.S. railroads during 1986, $10 was the average fine imposed.

What this tells us is that the FRA has taken all the preventive sting out of the rail safety programs. Even when the FRA finds defects and safety violations by carriers, the agency fails to carry out its obligation to impose fines as called for by federal laws, he said.

The association last week won a major challenge of mandatory drug testing rules in the U.S. Circuit Court of Appeals in San Francisco, which found the rules unconstitutional.

Mr. Kennedy and Larry Mann, the association's attorney for safety matters, said the unions would support drug testing if there was probable cause that an employee involved in an accident was under the influence and if drug-testing procedures were strengthened.

The decision, however, came just before the Conrail engineer in the bloodiest crash in Amtrak's history pleaded guilty to manslaughter in the deaths of 16 passengers about a year ago outside of Baltimore.

The engineer, Ricky L. Gates, admitted to having smoked a marijuana cigarette in the cab of the engine while he was operating it; he ran a signal and crossed into the path of a speeding passenger train.

The association's officials - Mr. Kennedy, Mr. Mann and Geoffrey N. Zeh of the Brotherhood of Maintenance of Way Employees - said they wanted the public to understand that drug testing is only a small part of the safety problem.

Mr. Kennedy said, We are willing to negotiate away our constitutional rights and submit to drug testing, if the probable cause and standardization elements are in place.

Mr. Zeh added that rail safety issues are of primary concern to the unions, since employees are most likely to be injured by rail accidents.

Mr. Kennedy said the labor executives' association would not support either of the two rail safety bills that have made it through the House and Senate. The bills should soon be the subject of a joint conference committee to iron out differences between them.

There are portions of both bills that we support and portions of both bills that we don't support, he said.

Specifically, Mr. Kennedy said, the unions opposed what Federal Railroad Administrator John H. Riley has called the most crucial part of both pending safety bills: the extension of FRA's safety authority to employees.

At present, the FRA regulates only the carriers, a factor which Mr. Riley has called the most inhibiting to an increased rail safety program.