Only 25,000 -- 2 percent -- of public and private workplaces with 10 or more employees sponsored day-care centers for their workers' children in 1987, according to a survey released yesterday by the Bureau of Labor Statistics.

Another 35,000 -- 3 percent -- provided some financial assistance to employees for day care but did not sponsor centers, the survey found.

The agency said another 6 percent, while not sponsoring day-care centers or providing other direct financial aid, gave one or more lesser forms of assistance, such as day-care referral services or counseling on family problems including day care.

Day care has become a major issue because of the huge increase in employed mothers. As recently as 1970, 30 percent of married women with children under six were in the labor force; by 1986, the figure was 54 percent, and for women with no husband in the household, 58 percent.

The survey, based on a sample of 10,000 establishments with 10 or more employees, found that large establishments with 250 or more employees are more likely than smaller ones to help with day care. In these larger companies, 5 percent sponsored centers, 9 percent provided financial aid and about 18 percent provided counseling, referral or similar assistance.

The survey also found that government agencies are more likely to provide some form of aid than private firms. Thus, while fewer than 2 percent of the private units sponsored centers, the figure was 9 percent for government units.

While direct sponsorship of a center or financial assistance to the employee was relatively rare, the agency found that 61 percent of workplaces had schedule policies that could make it easier to care for children, even if the policy was not instituted with that purpose in mind. These included flexible or part-time hours, flexible leave and arrangements to allow some work at home.