BEIJING (AP) — Two surveys show China’s manufacturing weakened in September as export demand shrank amid a tariff battle with Washington.

The official China Federation of Logistics & Purchasing said Sunday its monthly purchasing managers’ index declined to 50.8 from August’s 51.3 on a 100-point scale on which numbers above 50 show activity accelerating. A separate index by a business magazine, Caixin, fell to 50 from 50.6.

The logistics federation’s measure of new export orders tumbled to 48 from August’s 49.4. Caixin said its measure of new export business contracted at its fastest rate in more than two years.

The Trump administration raised tariffs last week on $200 billion of Chinese goods in a dispute over Beijing’s technology policy. China retaliated with penalties on $60 billion of American imports.