Robust job creation continued among private companies in the United States in April but was below the expected pace, payrolls firm ADP reported Wednesday.

The report showed the brisk pace of hiring was likely to continue to drive down the US unemployment rate even further and make qualified labor even harder for employers to find, ADP said.

ADP estimated companies added 204,000 employees last month, slightly below the 225,000 analysts had been expecting.

The Federal Reserve is not expected to raise benchmark interest rates later Wednesday when it announces its decision on monetary policy at the conclusion of a two day meeting.

But economists say the tight labor market, among other factors, means the Fed is increasingly likely to hike rates this year more aggressively than previously expected.

Ahu Yildirmaz, co-head of the ADP Research Institute, said skilled talent likely will become increasingly hard to find as jobs markets tighten.

"Job gains in the high-skilled professional and business services industry accounted for more than half of all jobs added this month," she said in a statement.

"The construction industry, which also relies on skilled labor, continued its six-month trend of steady job gains as well."

The report showed hiring slowed steadily since December, falling marginally in January, March and April, leaving last month at the lowest point since November.

Mark Zandi, chief economist at Moody's Analytics, which helped produce the report, said the current trend would soon drive unemployment from the current 4.1 percent to below four percent.

That low level "is rarified and risky territory as the economy threatens to overheat."

Companies already have reported having to raise wages to attract workers, and that tends to push up inflation, which will weigh on the Fed's decision making.