WASHINGTON (Reuters) - A measure of U.S. services sector activity slumped to a four-year low in June amid a sharp drop in orders, potentially hinting at a loss of momentum in the economy at the end of the second quarter.

The Institute for Supply Management said its nonmanufacturing purchasing managers (PMI) index dropped to 48.8 last month, the lowest level since May 2020, from 53.8 in May. It was the second time this year that the PMI had dropped below 50, which indicates contraction in the services sector.

Economists polled by Reuters had forecast the services PMI slipping to 52.5. The PMI fell below the 49 level that the ISM says over time generally indicates an expansion of the overall economy. The survey's business activity measure dropped to 49.6, the first contraction since May 2020, from 61.2 in May.

The ISM reported on Monday that manufacturing activity had deteriorated further in June.

The surveys, however, likely understate the economy's health, with so-called hard data like consumer spending suggesting a moderate pace of growth last quarter. The economy is adjusting to higher interest rates, which are slowing demand.

Growth estimates for the second quarter are around a 2% annualized rate. The economy grew at a 1.4% pace in the January-March quarter.

The survey's new orders measure dropped to 47.3, the lowest since December 2022, from 54.1 in May. Services employment continued to decline. That would suggest softer job growth in the months ahead, though the sentiment surveys have not been reliable predictors of payroll gains.

The government's closely watched employment report on Friday is likely to show nonfarm payrolls increased by 190,000 jobs in June after rising 272,000 in May, according to a Reuters survey of economists. The unemployment rate is forecast unchanged at 4%.

Services inflation slowed a bit last month. The ISM's prices paid measure for services inputs slipped to 56.3 from 58.1 in May. That suggests the disinflation trend was back on track after price pressures flared up in the first quarter.