WASHINGTON (Reuters) - U.S. prosecutors have asked a Brooklyn federal court judge to allow six officers of MI5, Britain's domestic counterintelligence agency, to testify anonymously and in disguise at the trial of an al Qaeda suspect, court documents and official sources said on Thursday.
A source close to the case said that if the spies were not allowed to conceal their identity, British authorities could refuse to allow them to give evidence at the trial, which is scheduled to begin early next month.
At a pre-trial conference on Wednesday, U.S. District Judge Raymond Dearie indicated he would consider the prosecutors' request but did not issue a final ruling, according to two sources close to the case.
Dearie requested that U.S. prosecutors ask MI5 to provide further justification for why its officers should be allowed to testify anonymously.
Abid Naseer is charged with providing material support for al Qaeda and on two conspiracy counts, including one of conspiring to use a destructive device.
A federal indictment says among Naseer's co-conspirators were Najibullah Zazi and Adis Medunjanin, two suspects in an alleged 2009 plot to attack New York subways.
In a letter to the judge earlier this month, prosecutors said that they wanted to call the MI5 officers to testify about surveillance they conducted of Naseer and other unnamed conspirators in March and April 2009 in connection with an alleged al Qaeda plot to stage an attack in Manchester, England.
In their January 15 letter to the judge, prosecutors said the MI5 officers wished to identify themselves only by a number rather than giving their names and wear "light disguises" including wigs and makeup.
One source close to the case said UK authorities were unaware of previous cases in which British spies were allowed to testify in U.S. courts anonymously. But prosecutors argued in their letter that U.S. appeals courts have sometimes allowed such testimony by law enforcement officers in the past.
The source said serving MI5 officers all operate undercover and are not allowed to reveal their employer or the nature of their work. Requiring them to appear in public under their real identities could put their safety and that of their families at risk, British security authorities have said.
Reporting By Mark Hosenball; Editing by David Storey and Christian Plumb