McDonald’s Japan is facing yet another food safety scandal after two customers found pieces of plastic in their Chicken McNuggets.

The first discovery, made on Saturday, spurred McDonald’s Japan to pull all 956,925 nuggets made by a Cargill unit in Thailand on the same day, in the same factory.

Despite the preventative action, another customer reported finding plastic inside a chicken nugget on Monday. McDonald’s is investigating, but has not yet said if the two incidents are related.

“We deeply apologize for the trouble we have caused our customers and we are taking quick measures to analyze the cause of the contamination,” said company spokesman Takashi Hasegasa.

The incidents are the latest in a string of food scares that have shaken Japanese consumer confidence in McDonald’s.

Among other incidents, a human tooth was found in a customer’s french fry in August, while a child in December cut his mouth on a piece of plastic that was in a chocolate sundae.

Last July, the company was among several fast food chains to be hit by a scandal involving tainted meat from a Chinese supplier.

Sales at McDonald’s Japan have dropped more than 10 percent every month compared to the same period last year since the food scare hit, even after the company switched to suppliers in Thailand. The company has said it expects to post a net loss for its current fiscal year — the first annual loss in 11 years — as a result.