Australia's domestic spy agency has backed controversial legislation which would force telecommunications companies to store phone and internet data for two years.
The Australian Security Intelligence Organisation (ASIO) says basic communications data from phones and emails, such as when a call was made or whom an email was sent to, is vital for gathering evidence.
ASIO has given an unclassified submission to a parliamentary committee, saying telecommunications companies have traditionally kept the data to bill customers but new technology means there is less need to do so.
It says the legislation will not give it access to the content of calls or emails, just the time they were sent or who they were sent to.
ASIO says this type of data retention leads to tip-offs about terrorist cells and can confirm intelligence reports.
The agency says it would support new penalties to stop the misuse of the powers.
The Government has not made a final decision on the laws, while the The Greens say the legislation poses a threat to privacy.
Optus says storing the data will be expensive.