A federal judge has resigned from the court that oversees government surveillance in intelligence cases in protest of US President George W. Bush's authorisation of a domestic spying programme, The Washington Post reported on Wednesday.
Citing two sources, the newspaper reported US District Judge James Robertson, one of 11 members of the Foreign Intelligence Surveillance Court, known as FISA, sent his resignation to Chief Justice John Roberts on Monday.
The Post said the resignation letter gave no explanation for Robertson stepping down. Robertson declined comment when reached on Tuesday, the newspaper said.
Robertson is considered a liberal judge who has often ruled against the Bush administration's assertions of broad powers in the terrorism fight, the Post said.
Revelation that authorised domestic spying on Americans suspected of terrorists links without court approval spurred considerable debate among federal judges, including some on the FISA Court, The Washington Post said.
The Post said Robertson indicated privately to colleagues in recent conversations that he was concerned that information gained from warrantless National Security Agency surveillance could have then been used to obtain FISA warrants.
FISA court Presiding Judge Colleen Kollar-Kotelly, who had been briefed on the NSA spying programme, raised the same concern in 2004 and insisted that the Justice Department certify in writing that it was not occurring, the Post said.
"They just don't know if the product of wiretaps were used for FISA warrants - to kind of cleanse the information," one source, who spoke on the condition of anonymity, was quoted as saying.
Robertson was appointed to the federal bench in Washington by President Bill Clinton in 1994. He was later selected by then-Chief Justice William Rehnquist to serve on the FISA court, the Post said.