The US National Security Agency has collected almost 200 million mobile phone text messages a day from around the world, a report said Thursday, in the latest revelations from the Edward Snowden files.

The Guardian newspaper and Britain's Channel 4 News reported that the NSA used the messages to extract data on the location, contact networks and credit card details of mobile users.

British spies were given access by the NSA to search the collected "metadata" -- information about the text messages but not the actual contents -- of British citizens, according to the report.

The secret files say the programme, codenamed Dishfire, collects "pretty much everything it can", the Guardian and Channel 4 News reported.

Dishfire works by collecting and analysing automated text messages such as missed call alerts or texts sent to inform users about international roaming charges, the news organisations said.

It was also able to work out phone users' credit card numbers using texts from banks.

They cited an internal NSA presentation from 2011 on the programme and papers from Britain's electronic eavesdropping facility GCHQ.

There was no immediate reaction from the NSA.

GCHQ said it worked within British law.

"All of GCHQ's work is carried out in accordance with the strict legal and policy framework which ensures that our activities are authorised, necessary and proportionate and that there is rigorous oversight," it said in a statement.

The NSA also said its collection of text messages was carried under strict limits under the law and was not arbitrary.

"DISHFIRE is a system that processes and stores lawfully collected SMS data," the spy agency said in a statement.

"Because some SMS data of US persons may at times be incidentally collected in NSA's lawful foreign intelligence mission, privacy protections for US persons exist across the entire process concerning the use, handling, retention, and dissemination of SMS data in DISHFIRE," it said, adding that any data on innocent foreign nationals was also removed promptly.

The report comes a day before US President Barack Obama is due to give a long-awaited speech proposing curbs on NSA phone and Internet data dragnets exposed by fugitive intelligence contractor Snowden.

Snowden remains in exile in Russia, where he has been granted temporary asylum.

The president discussed the details of Friday's speech during a telephone call with British Prime Minister David Cameron on Thursday, according to Cameron's Downing Street office.

During the discussion, the two leaders "welcomed the unique intelligence sharing relationship between their two countries," according to the statement.