WASHINGTON – In another sign of tepid growth, U.S. private-sector firms created a lackluster 13,000 jobs in June, according to a report released Wednesday by payroll company ADP.

Hiring was “disappointingly weak” in June, said Joel Prakken, chairman of Macroeconomic Advisers, which produces the report from anonymous data supplied by ADP.

Some economists lowered their estimates for this Friday’s nonfarm payrolls report after the weak ADP numbers, and others said the risks had risen that Friday’s report could be weaker than they are forecasting.

Still, economists surveyed are forecasting stronger private-sector job growth of 115,000 when the Bureau of Labor Statistics reports on Friday.

The ADP report doesn’t include govern-ment workers. In June, about 240,000 temporary workers at the U.S. Census lost their jobs, and thousands of state and local government workers may have been laid off. As a result, overall nonfarm payrolls are expected to fall by 130,000 in June, according to MarketWatch’s survey of top economists.

Given the wide swings in temporary employment over the past two months, most economists have been focusing their attention on the trend in private-sector jobs, not total employment.

After dropping by 8.28 million during the recession, private-sector employment has increased five months in a row, averaging a “lethargic” 34,000, said Prakken. The 13,000 gain in June was the weakest since February’s addition of 3,000 private jobs.

The ADP report has been significantly weaker than the official Bureau of Labor Statistics survey of business establishments, which have reported an average monthly increase of 99,000 in private-sector payrolls so far this year.