Cement is laid on the San Joaquin River viaduct portion of the high-speed rail line being built in Fresno, California, on May 8, 2019, amid ongoing construction of the railway in California's Central and San Joaquin Valleys.

Growth in the U.S. services sectors decelerated in July to its weakest level in three years as trade worries weighed on business orders and the outlook for the overall economy, a private survey released on Monday showed.

The Institute for Supply Management (ISM) said its non-manufacturing activity index fell to 53.7 from 55.1 the month before. Analysts polled by Reuters had forecast a reading of 55.5 for July.

A reading above 50 indicates expansion in the sector.

Slower growth in the services sector, which accounts for more than two-thirds of U.S. economic activity, comes at a time that the U.S.-China trade war has been squeezing manufacturers.

"For an economy that is so heavily dependent on the service sector, this is a particularly troubling release," Ian Lyngen, head of U.S. interest rates strategy at BMO Capital Markets wrote in a research note.

The ISM services survey's measure on new orders fell to 54.1 last month, its lowest since August 2016, from 55.8.

A barometer on new export orders fell to 53.5 from 55.5 in June.

The latest reading on services prices fell to 56.5 from 58.9.

A lone bright spot was an uptick in the employment index, which moved up to 56.2 from 55.0.