Federal prosecutors want to disqualify the former deputy attorney general who is defending the Chinese telecommunications giant Huawei Technologies in a bank fraud case because the government believes his previous work for it poses a conflict of interest.

In a filing on Friday in federal court in Brooklyn, prosecutors said the attorney, James M. Cole, should not be permitted to represent Huawei because he had been briefed on an undisclosed investigation while serving as a top prosecutor in the Obama administration.

The filing is redacted, making it difficult to ascertain the exact nature of the investigation. But Mr. Cole’s tenure at the Department of Justice — from the end of 2010 to the beginning of 2015 — may have overlapped with the period when federal authorities were gathering information on Huawei and its business dealings.

Mr. Cole is now co-head of the white-collar and investigations practice at the Sidley Austin law firm. A spokeswoman for the firm did not respond Friday to requests for comment on the disqualification attempt.