Video shows a man dressed in a hard hat and blue overalls climbing down into a malt container at the Chinese beer factory in Pingdu, unzipping his trousers and relieving himself.

Tsingtao, which describes itself as the sixth-largest global beer maker, said they have sealed all batches linked to the incident.

They said in a statement: "Our company attaches high importance to the relevant video that emerged from Tsingtao Brewery No. 3 on 19 October.

"We reported the incident to the police at the earliest opportunity, and public security organisations are involved in the investigation.

"At present, the batch of malt in question has been completely sealed. The company continues to strengthen its management procedures and ensure product quality."

Read more from Sky News:
US warns China after Philippines collision
Hamas has six British hostages, government fears

A source told local outlet Yicai that the man filmed is not a Tsingtao employee, but a loader hired by a third-party labour supplier.

However, the incident damaged Tsingtao, as shares on the Shanghai Stock Exchange dropped by 1% on Friday and by 7.5% on Monday morning.

Users on Weibo, where the video was originally posted on Thursday, mocked the situation.

"Good thing I don't drink beer - but it's unimaginable if this brand is finished because of this," one user said.

"I've always said the beer here is like horse pee," another added. "Turns out I was wrong."