NEW YORK (AP) — McDonald’s says a key sales figure fell 2.5 percent in July, dragged down by persistent weakness in the U.S. and the impact of a food safety scandal in China.

The world’s biggest hamburger chain says the global decline included a 3.2 percent drop in the U.S. and a 7.3 percent drop in Asia, the Middle East and Africa.

The company, based in Oak Brook, Illinois, has been struggling to boost sales in the U.S. amid heightening competition and shifting eating habits.

In China, sales took a significant hit after a TV report showed workers at one of its suppliers repackaging expired meat. Many restaurants there were unable to serve burgers and chicken as a result.

McDonald’s Corp. said the scandal has put its global sales forecast for 2014 “at risk.”

Its shares slipped in premarket trading Friday.