A judge has ruled that British intelligence officers can testify in disguise at the U.S. trial of an alleged al-Qaida operative.

Judge Raymond Dearie gave the go-ahead on Wednesday. Federal prosecutors told him the disguises are needed to protect the undercover status of the MI5 agents.

Authorities say the agents conducted surveillance on Abid Nasser while investigating a failed plot to bomb a mall in Manchester in 2009.

He's pleaded not guilty to charges he was part of broader conspiracy that included another al-Qaida plot to bomb New York City subways.

Prosecutors say the trial will feature evidence seized during the Navy Seal raid in 2001 that left Osama bin Laden dead.

The trial is set to begin next month in Brooklyn.