BEIJING — China's manufacturing activity improved in August but sales weakened amid a worsening tariff war with Washington, a survey showed Friday.

The China Federation of Logistics & Purchasing said its monthly purchasing managers' index rose to 51.3 from July's 51.2 on a 100-point scale on which numbers above 50 show activity expanding. Components for new orders and exports declined, suggesting demand is weakening.

"The trade war's impact increasingly appeared in the data," said Citigroup economists in a report.

Washington and Beijing have imposed tariff hikes on $50 billion of each other's goods. President Donald Trump is poised to impose penalties on an additional $200 billion of Chinese imports as early as next week. Beijing has said it will retaliate.