Federal prosecutors in Brooklyn, New York, said they’ve filed a motion to disqualify a lawyer representing Huawei Technologies Co. and Huawei Device USA, which have been accused by the U.S. of defrauding banks by concealing business dealings in Iran.

In a letter to U.S. District Judge Ann Donnelly, the government said Thursday that it has filed a “sealed classified motion” to disqualify James M. Cole, a former top lawyer with the U.S. Justice Department and currently a partner at Sidley Austin LLP. No explanation for the request was given. Prosecutors said they’ll file a public version of their motion with the court by May 10.

Prosecutors claim Huawei employees, including Meng Wanzhou, Huawei’s chief financial officer, lied to at least four banks since 2007 about the company’s relationship with Skycom Tech Co., which operated in Iran. Huawei and Meng falsely claimed Skycom wasn’t an affiliate, according to the government.

Cole, who served as deputy attorney general from 2011 to 2015 under Attorney General Eric Holder, declined to comment about the government’s letter.