Huawei Technologies Co Ltd lawyer James Cole’s prior work at the US Department of Justice created conflicts of interest that should disqualify him from defending the Chinese company in a case of alleged bank fraud and sanctions violations, US prosecutors said in a filing on Friday.

Last week, the prosecutors filed a motion to disqualify Cole, who served as deputy attorney general, the number two at official at the Justice Department, between 2011 and 2015.

But the motion was sealed and classified, and prosecutors did not make public the reasons behind the move.

“There is a ‘substantial risk’ that Cole could use ‘confidential factual information’ obtained while serving as DAG to ‘materially advance’ Huawei’s current defense strategy,” the prosecutors said, according to a redacted copy of the US motion filed on Friday in US District Court in Brooklyn, New York.

Cole was not immediately available for comment. But in a statement Huawei said the US wants to strip the company of counsel of its choice while concealing the facts on why.

“The Justice Department’s motion to disqualify Jim Cole makes a mockery of the adversarial process,”the statement said.

“The government has known since 2017 that Mr. Cole represented Huawei in this matter. Now, two years later, not only does the Justice Department seek to strip Huawei of counsel of its choice, but it does so while concealing from Huawei and the public virtually all of the facts on which it bases its motion.”

The case against Huawei, the world’s largest telecommunications equipment maker, has ratcheted up tensions between Beijing and Washington as the world’s top two economic powers try to negotiate a trade deal.

The company’s chief financial officer, Meng Wanzhou, daughter of Huawei’s founder, was arrested in Canada in December at the behest of U.S. authorities for her role in the alleged fraud. Meng has said she is innocent and is fighting extradition.