A huge revelation in the Huawei case, via Bloomberg: the US government has been spying on Huawei Technologies and company officials to build its case against CFO Meng Wanzhou based on authorization from America's highest secretive intelligence court:

U.S. prosecutors said the government secretly conducted electronic surveillance and collected information in its criminal case against Huawei Technologies Co. using the Foreign Intelligence Surveillance Act, or FISA.

Huawei CFO Meng Wanzhou, now being held in Canada.

The breaking report describes that the revelation came out in court during a hearing on Thursday:

Assistant U.S. Attorney Alex Solomon told U.S. District Judge Ann Donnelly in Brooklyn, New York, at a hearing Thursday that prosecutors wanted to put Huawei and its American lawyers on notice that the U.S. had collected such evidence, which he described in a filing as "electronic surveillance and physical search using a FISA warrant, conducted under the Foreign Intelligence Surveillance Act."

U.S. prosecutors filed criminal charges against Huawei in late January alleging that China’s largest smartphone maker stole trade secrets from an American rival and committed bank fraud by violating sanctions against doing business with Iran.

Meng was arrested in Canada at the request of the US, who has since sought her extradition to face criminal charges. The Supreme Court of British Columbia in Vancouver will hold her first extradition hearing on May 8, which she has sought to fight.

The US government's 13-count indictment charged that Huawei, two affiliated companies and its chief financial officer engaged in fraud and conspiracy in connection with deals in Iran.

A separate 10-count indictment in Seattle accused the company of stealing trade secrets from T-Mobile USA Inc. and offering bonuses to employees who succeeded in getting technology from rivals.

Prosecutors in Brooklyn on Thursday wouldn't elaborate further on specific evidence obtained through America's most secretive court (FISA). According to Bloomberg:

There wasn’t any indication what the evidence might be and prosecutors didn’t elaborate further. Solomon declined to comment after the hearing. Huawei’s lawyer James Cole also declined to comment.

The criminal case against Huawei first emerged in 2014, when T-Mobile USA sued the Chinese telecom giant, and three years later, a federal jury in Seattle found Huawei liable for both breach of contract and misappropriation of trade secrets.

Wanzhou has since become a flash-point in trade tensions between the US and China — tensions which will no doubt rise with these latest revelations of US spying on the Chinese firm, authorized at the highest levels of US intelligence.