WASHINGTON - The US Congress should pass a law to give investigators freer access to certain cellphone records, an Obama administration official said on Thursday, in remarks that raised concern among advocates of civil liberties and privacy.

Jason Weinstein, a deputy assistant attorney general in the Justice Department's criminal division, argued that requirements for warrants at early stages of investigations would "cripple" prosecutors and law enforcement.

The US Supreme Court ruled this year that a warrant was needed to put a GPS satellite tracking device on a suspect's vehicle, prompting questions about other instances where probable-cause warrants should be needed to obtain information in the rapidly changing world of mobile devices.

Federal courts around the country are split on whether to require warrants for records of phone usage collected at towers that transmit cellphone signals, Weinstein told a conference.

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