Shares of Hong Kong-based beverage company, Vitasoy, dropped by the most Monday after an internal memo triggered an online call for the boycott of its products. A staff member reportedly leaked the memo, which offered condolences to the family of a worker who stabbed a Hong Kong police officer.

Vitasoy published a post on its official Weibo account Monday, stating that the release of the memo was "extremely inappropriate." The company said the staff member circulated the memo without authorization and it is prepared to take immediate legal action.

Vitasoy's share price dropped by more than 14.6% to HK$25.1 per share - the largest single-day drop since the company went public in 1994.

The memo offered condolences to the family of a 50-year-old employee at the company. The worker reportedly stabbed a 29-year-old police officer last week before taking their own life. The officer that was attacked is reportedly now out of critical condition.

Hong Kong authorities described the stabbing of the police officer during the anniversary of the city's return to Chinese rule as a "terrorist attack." Authorities seized the worker's computer from his home, which they claimed showed how the "lone wolf" had been "radicalized." Authorities did not elaborate on how the man had been radicalized.

The publication of the memo immediately sparked a wave of online protests against the company in mainland China, including calls for a nationwide boycott of its products.

Vitasoy generates more than two-thirds of its revenues from mainland customers. The company, which was founded in 1940, offers a variety of flavored soy-based drinks as well as a range of non-soy plant milk. It also offers different brands of coffees, juices and teas.

Chinese actor, Gong Jun, joined in the protest. The actor, who had been endorsing Vitasoy's products, said in a post online that he was ending his commercial contract with the company. Other celebrities soon followed, including mainland Chinese actor, Ren Jialun.

Hong Kong authorities said Monday that calling on people to mourn for the attacker is no different from "supporting terrorism." Authorities warned people that such acts should not be encouraged.