Citing government officials who spoke on Friday, the newspaper reported that the proposal, to be considered next week in a closed-door Senate Intelligence Committee meeting, would allow the FBI to direct postal officials to turn in names, addresses and other material on the outside of letters sent to or from people connected to foreign intelligence investigations.

But the Postal Service is raising privacy concerns about the plan to carry out such operations, called mail covers, the Times said.

According to a draft of the bill obtained by the Times, the plan would effectively eliminate postal inspectors' discretion in deciding when mail covers are needed, giving sole authority to the FBI, if it decides that the material is "relevant to an authorized investigation to obtain foreign intelligence."

The proposal would not allow the FBI to open mail or review its contents, however. According to the officials who spoke to the Times, that would require a search warrant.

The proposal is part of a larger package that strengthens the FBI's authority to demand business records in intelligence gathering without judicial or grand jury approval, the Times said.

A postal official called the move a "major step." Zoe Strickland, chief privacy officer for the Postal Service, told the Times that "from a privacy perspective, you want to make sure that the right balance is struck between protecting people's mail and aiding law enforcement, and this legislation could impact that balance negatively."

The Times quoted Strickland as saying that the new proposal "removes discretion from the Postal Inspection Service as to how the mail covers are implemented," and that she worries "quite a bit about the balance being struck here, and we're quite mystified as to how this got put in the legislation."

Officials on the Intelligence Committee said the legislation was intended to make the FBI the sole arbiter of when a mail cover should be conducted, after complaints that undue interference from postal inspectors had slowed operations, the Times said.