AstraZeneca, the largest foreign pharmaceutical company in China, said on Wednesday that its China president, Leon Wang, was being investigated on the mainland, and that he had been cooperating with an ongoing inquiry.

The case appeared to be the first such investigation of a high-ranking executive for a foreign company in China in recent years.

Chinese foreign ministry spokesman Lin Jian did not confirm or deny the news on Thursday.

“China will protect foreign companies investing in China and protect their legitimate rights and interests in accordance with the law,” Lin said, without offering a reason for the investigation, giving any details about Wang’s whereabouts, or confirming whether he was in custody.

Chinese investigators were looking into aggressive sales tactics for the firm’s oncology drugs, Bloomberg reported, citing people familiar with the matter.