More leaked U.S. intelligence documents have revealed Australian spies were helping their American counterparts to secretly monitor telephone calls across the Philippines. According to the secret documents of the U.S. National Security Agency unveiled by former intelligence contractor Edward Snowden, the Australian Signals Directorate provides support to an NSA intelligence collection programme MYSTIC.

The secret documents revealed that the Australian electronic spy agency collects telecommunications "metadata" around the world, including countries like the Philippines. The Intercept news Web site has previously published top secret information about the MYSTIC programme, using data collection systems installed in mobile devices for legal commercial services. However, the systems are also being used for a "covert mission."

According to reports, the collection of telecommunications metadata includes the source, time and destination of people's phone calls and text messages. The metadata contains intimate details on individuals and their relationships with other people, companies and organisations.

A NSA document in 2013 has revealed a comprehensive gathering of telecommunications data in the Philippines using the MYSTIC programme. The collection is overseen by the Australian Signals Doctorate, formerly known as the Defence Signals Directorate. Australian and U.S. access to Philippine telecommunications data is provided by a "DSD assed in a Philippine provider site" which collects text messages and calls.

The NSA noted in the 2013 document that the Australian surveillance in the country will "soon become a source of lucrative intelligence" for alleged "terrorist activities in the Southern Philippines." Aside from the Philippines, the MYSTIC programme also covers Mexico and Kenya.

Australians are not exempt from mass surveillance by the country's own spy agency. On May 13, documents from the U.S. National Security Agency published in the book No Place to Hide: Edward Snowden, the NSA and the Surveillance State by Glenn Greenwald revealed new details regarding Australia's close relationship with NSA.

Australia has sought the help of the Americans to increase surveillance on suspected terrorists. According to The Guardian, Australia's intelligence agency needed the help of the U.S. spy agency to monitor Australians suspected of having ties with extremists. The country's defence department has refused to comment on the matter, according to reports.