The elite Wall Street law firm Sullivan & Cromwell has told a court that a major filing it made in a high-profile case contained errors resulting from hallucinations generated by artificial intelligence.

Andrew Dietderich, the co-head of the firm’s global restructuring group, apologised in a letter to the New York federal judge Martin Glenn on Saturday for the string of mistakes, which included inaccurate citations.

The errors, uncovered by the law firm Boies Schiller Flexner (BSF), which was also working on the case, included misquoting the US bankruptcy code and citing cases incorrectly in a filing made on 9 April.

In multiple instances, S&C, which employs more than 900 lawyers and has one of the top reputations for corporate work in the US, filed inaccurately summarised conclusions made in other cases using AI.

“We deeply regret that this has occurred,” said Dietderich in the letter. “I apologise on behalf of our entire team. I also called BSF on Friday to thank them for bringing this matter to our attention and apologise to them directly as well.”

The firm said that it maintains “comprehensive policies and training requirements governing the use of AI tools in legal work” that are designed to catch any potential errors.

However, the letter said those AI policies were not followed and that a secondary review process also “did not identify the inaccurate citations generated by AI”.

S&C later filed a corrected version to the court. Lawyers are not prohibited from using AI but are ethically bound to ensure the accuracy of court submissions.

The letter did not say which AI program was used to help produce the court filing, or which lawyers prepared the document, and whether any action had been taken against them as a result of the AI mistakes.

The case involved S&C’s representation of liquidators appointed by legal authorities in the British Virgin Islands who are engaged in actions against Prince Group, which is owned by the Chinese-born businessman Chen Zhi.

Last year, US prosecutors charged Chen with wire fraud and money laundering, alleging that he directed “Prince Group’s operation of forced-labour scam compounds across Cambodia … that stole billions of dollars from victims in the United States and around the world”.

In a statement last year, Prince Group denied that Chen had committed wrongdoing and called the allegations baseless.

Separately, US prosecutors also filed a legal action to seize nearly $9bn of bitcoin that US authorities alleged represented the proceeds of the Prince Group’s criminal activity.

Chen was arrested earlier this year in Cambodia and extradited to China upon the request of Chinese authorities.