A trader pauses at his desk ahead of the closing bell on the floor of the New York Stock Exchange (NYSE), January 22, 2019 in New York City.

U.S. manufacturer growth hit a multiyear low in May, the latest sign that the trade war may be slowing the economy.

The U.S. manufacturing PMI (purchasing managers index) was 50.6 in May, the lowest level since September 2009, according to results from financial data firm IHS Markit released Thursday.

"Growth of business activity slowed sharply in May as trade war worries and increased uncertainty dealt a further blow to order book growth and business confidence," said Chris Williamson, Markit's chief business economist.

U.S. overall business activity growth also faltered to a three-year low as the seasonally adjusted IHS Markit Flash U.S. Composite PMI Output Index dropped to 50.9 in May, indicating the slowest expansion since May 2016.

"The slowdown has been led by manufacturing, but shows increasing signs of spreading to services...Trade wars remained top of the list of concerns among manufacturers, alongside signs of slower sales and weaker economic growth both at home and in key export markets," Williamson said.

Trade tensions between the world's two largest economies intensified this month after both sides slapped tit-for-tat tariffs on billions of dollars worth of each other's goods. President Donald Trump also toughened his stance on trade this week by blacklisting Chinese telecom giant Huawei, halting its ability to buy American-made parts and components.