Hang Seng Bank has become the fifth lender to sue former chief secretary Rafael Hui Si-yan for debt repayment, seeking to reclaim more than HK$780,000.
The bank said in its writ, filed with the District Court, that Hui owed the money through an overdraft and credit-card loans.
Hui, 65, is already embroiled in the most high-profile corruption case in Hong Kong's history with Sun Hung Kai Properties co-chairmen Thomas Kwok Ping-kwong and Raymond Kwok Ping-luen.
The latest legal action takes Hui's debt burden to almost HK$75 million, including an unconfirmed HK$60 million due to the Bank of East Asia, which has filed a petition to bankrupt him.
Hang Seng says in its writ that, up to September 25, Hui had HK$633,656 outstanding in his overdraft account and owed another HK$146,844 on his credit card.
Lawyers for the bank asked him last month for the amount due, but he failed to pay up, the writ says.
Apart from Hang Seng, Hui faces at least four other claims from different creditors.
The BEA filed the first case against Hui, asking in April for payment of all money due under two overdraft facilities and two credit cards. BEA chairman David Li Kwok-po later said Hui was repaying the bank in instalments.
Media reports last year said Hui owed the bank HK$60 million. The bankruptcy hearing will be heard in the High Court on November 20.
In mid-August, Honour Finance, a company owned by Sun Hung Kai Properties, filed two writs to retrieve HK$3.16 million in a loan for which Hui acted as a guarantor.
A week later, Chong Hing Bank launched a suit to claim an outstanding amount of more than HK$9.8 million.
As the month drew to a close, Standard Chartered Bank issued a writ for HK$1.19 million plus interest after Hui drew loans on four credit cards and took out a personal overdraft.
In March this year, Hui and the Kwok brothers and two others pleaded not guilty to multiple charges filed by the Independent Commission Against Corruption.
The allegations against Hui include misconduct in public office. The charge alleges that when he was the chief secretary from June 2005 to June 2007, he failed to declare or disclose provisions and annual extensions of a HK$3 million unsecured loan from Honour Finance - the claimant in one of the civil suits. The criminal trial is due to be heard in May.