A controversial "workfare" measure supported by the liberal Democratic administration of Gov. Harry Hughes has drawn strong opposition from organized labor and welfare advocacy groups that initially hoped to support it.

The bill, sponsored by House Minority Leader Raymond L. Beck (R-Carroll), would give authority to the state's Department of Human Resources to begin a test program that could require adult welfare recipients to take jobs in the public and private sectors or risk losing their welfare grants.

About 700 Marylanders now take part in a program that requires them to pay off their grants by working in public sector jobs, primarily in state agencies. Welfare lobbyists say the new bill could affect 70,000 welfare families. For the first time, it would allow the state agency to place welfare recipients in jobs in the private sector.

Religious, labor, and welfare advocacy groups, including the state AFL-CIO and League of Women Voters, oppose the bill because it does not guarantee day-care services for welfare mothers who are put to work or provide assurances that "workfarers" would receive prevailing wages. Although there is a provision in the bill that would prevent private employers from replacing their own workers with those on welfare, some opponents of the measure still are skeptical.

"All it does is create unemployment and put an additional burden on the unemployed," says Thomas M. Bradley, head of the state AFL-CIO. "It would be impossible to enforce, especially in areas where the unemployment rate is as high as 18 percent."

Critics also charge that the measure is unduly "punitive," forcing welfare recipients into jobs they may not be suited for by threatening them with lost benefits. This mandatory provision, one lobbyist has said, "is likely to create an expensive and bulky sanctioning mechanism that costs more to administer than it saves."

Some opponents of the bill initially planned to support it. But they changed their minds when state welfare officials succeeded last month in deleting several protections from the bill, including ones that would have guaranteed wages comparable to other workers, as well as safe working conditions, transporatation expenses, and medical coverage for persons participating in the workfare program.

"We share the sponsor's interest in providing employment and training opportunities to recipients. But our concern is that the bill as amended sets a framework for an ineffective and punitive work program," says a letter from Cheryl D. Lynch of Associated Catholic Charities of Baltimore, which has reversed its original position in favor of the bill, to Del. Tyras S. Athey (D-Anne Arundel), chairman of House Ways and Means Committee, which is scheduled to vote on it Friday.

State welfare officials said the provisions were excluded from the current version so that it would comply with new federal welfare laws and enable the agency to apply for federal matching money.

State Human Resources Secretary Kalman R. Hettleman has said that despite the absence of the protections, the agency would not force mothers to work unless day care was available and would exempt the disabled and would consider other factors that might prevent ablebodied adults from working. He has emphatically denied suggestions that workfare amounts to "slave labor."

But welfare advocates, many of whom trust Hettleman and other officials in his agency, worry that a failure to include guarantees in the bill could lead to a more punitive program if a more conservative governor or state administration comes into office.

Some welfare advocates say they are worried that the proposal would fail due to inadequate funds, a historic problem with workfare experiments in other states. The experience for the welfare recipient could end up more humiliating than helpful, one lobbyist suggested, if funds were not available for proper counseling and training, not to mention day care and work bonuses.

State officials have tried to portray the "workfare" proposal in Maryland in a different light from programs in other states, notably one in California. That program, begun when President Reagan was governor, has since been repealed because it was ineffective. A state study concluded that the program failed to return welfare recipients to the work force.

The proposal outlined by Maryland officials would consist of a three pilot programs in different parts of the state, each providing counseling in job hunting, job training, and subsidies to employers who hire welfare workers. The actual costs have not been determined, except for an initial $2.6 million for the job search program, according to state officials.