Image caption Verizon receives requests from law enforcement agencies for customer data

US mobile operator Verizon says it will reveal the number of requests for customer information it received from law enforcement agencies this year.

The move follows leaks about mass surveillance programmes run by the National Security Agency from fugitive ex-NSA contractor Edward Snowden.

Shareholders asked Verizon to disclose its dealings with the NSA last month.

The company says it will publish total requests received in criminal cases, as well as details on other legal demands.

This will include court orders, subpoenas and warrants.

The aim of our transparency report is to keep our customers informed about government requests for their data and how we respond to those requests Randal Milch, Verizon

'Transparency'

But Verizon, the second-largest US telephone company by revenue, says it is still working with the US government to establish the amount of information it can legally reveal about the number of national security letters it received. The letters are legal orders allowing the government to demand financial and phone records without prior court approval.

The report will also not publish "information about other national security requests received by the company".

"The aim of our transparency report is to keep our customers informed about government requests for their data and how we respond to those requests," Randal Milch, executive vice-president of public policy at Verizon, said in a statement.

"Verizon calls on governments around the world to provide more information on the types and amounts of data they collect and the legal processes that apply when they do so."

Much of the information it plans to reveal is already on available on an ad hoc basis, but the report - to be published in early 2014 and updated twice a year - aims to make it more consistently available, Mr Milch said.

More freedom

Several major internet companies, including Google, Microsoft, Apple, Facebook and Yahoo, already publish periodic reports disclosing the number of requests from federal agencies and police departments for personal data.

They have called for more freedom to disclose information on national security-related requests. Eight firms formed an alliance called Reform Government Surveillance earlier this month.

Verizon says its report will detail requests "to the extent permitted by applicable US and foreign laws and regulations".

Apple, Microsoft, Yahoo, Google and Facebook have all confirmed they have complied with orders to hand over data relating to "national security matters" to the US authorities.

However, they have been forbidden from saying exactly how many requests they received or details about their scope.

A White House panel has recommended significant curbs on the National Security Agency's electronic surveillance programme following a ruling from a federal judge finding it unconstitutional.

Mr Snowden, an ex-US contractor granted temporary asylum in Russia, leaked documents to the media highlighting the various methods used by agencies to gather information.

The leaks have pointed to agencies collecting phone records, tapping fibre-optic cables that carry global communications and hacking networks.

That has lead to concern among users over how much customer information companies have been sharing with authorities.