HSBC told its staff to stop posting on all the bank's social media accounts over fears of "negative reactions" to the revelations in leaked suspicious activity reports.

In a memo to employees on Monday, Tricia Weener, head of marketing for HSBC's global commercial and investment banking arms, said the London-based company would not post until at least 11:00 am UK time Tuesday.

"Given the current news coverage, a decision has been taken to pause all HSBC proactive social media posts with immediate effect (except for customer responses in banking services), to avoid negative reactions and comments across our channels and content," wrote Weener.

Shares in HSBC fell 2.7% to HK$28.50 in Hong Kong as of 10:45 a.m. local time, after reaching the lowest since 1995 Monday.

HSBC is one of about 90 banks named in the leaked documents from the US Department of Treasury's Financial Crimes Enforcement Network, which showed about $2 trillion in transactions between 1999 and 2017 that were flagged by financial institutions' internal compliance officers as possible money laundering or other criminal activity.

In HSBC's case, the documents say it processed million of dollars in transactions for a Chinese Ponzi scheme, leaving victims of the scam unable to recoup losses. "Starting in 2012, HSBC embarked on a multiyear journey to overhaul its ability to combat financial crime across more than 60 jurisdictions. HSBC is a much safer institution than it was in 2012," the bank said in response to the stories by BuzzFeed News and the International Consortium of Investigative Journalists.

The bank operates dozens of social media accounts across the world, providing information on its services to customers in all the major countries where it operates. HSBC revealed through its official WeChat account in June that its most senior Asia-based executive signed a petition backing a new national security law for Hong Kong, drawing criticism from Western politicians.

A spokesperson for HSBC in London declined to comment.