NEW YORK, Jan 17: Months after the September 11 attacks, the National Security Agency began sending a plethora of telephone numbers, email addresses and names to the FBI in search of terrorists but virtually all of them led to dead ends or innocent Americans, the New York Times said on Tuesday.

The stream of messages soon became a flood, requiring hundreds of agents to check out thousands of tips a month, current and former officials told the Times.

The newspaper said that the FBI officials repeatedly complained to the spy agency that the unfiltered information was swamping investigators. The spy agency was collecting much of the data by eavesdropping on some Americans’ international communications and conducting computer searches of phone and internet traffic.

Some FBI officials and prosecutors also thought the checks, which sometimes involved interviews by agents, were pointless intrusions on Americans’ privacy.

As the bureau was running down those leads, its director Robert S Mueller raised concerns about the legal rationale for a programme of eavesdropping without warrants, one government official said. Mr Mueller asked senior administration officials about “whether the programme had a proper legal foundation,” but deferred to Justice Department legal opinions, the official told the newspaper.

Several of the law-enforcement officials acknowledged that they might not know of arrests or intelligence activities overseas that grew out of the domestic spying programme.