West Australian Greens Senator Scott Ludlam says his iPhone may have been hacked by the federal government so it could keep tabs on an internet activist.

Ludlam told Crikey from New Zealand this morning that his iPhone had been exhibiting strange behaviour consistent with external interception when he escorted former WikiLeaks spokesman Jacob Appelbaum from Ballarat to Melbourne last Friday.

The US-based Appelbaum is a key developer of The Tor Project, which helps users connect anonymously to the internet. He has been under close watch by US government operatives for years and until late last year was regularly detained at airports when re-entering the US. He is was also one of several WikiLeaks associates who were the subjects of a secret Department of Justice order to force Twitter to release private data part of an investigation into the leaking of US diplomatic cables.

The duo were travelling to a forum — The War on the Internet — held at Trades Hall in Melbourne on Saturday. During the commute, Senator Ludlam’s iPhone began to die.

“I was Jacob’s chaperone back from Ballarat to Melbourne for the forum … and I discovered first thing in the morning that the battery was being chewed through freakishly quickly,” Ludlam told Crikey. “I needed to put another other charge on it by about 10 or 10.30 in the morning. So it was being eaten up two or three times faster than normal.”

Appelbaum explained his phone may have been “off”, in the language of the intelligence services.

“That’s one symptom if the transmitter’s been switched on remotely so it’s basically broadcasting whatever it’s hearing … that would be one reason the battery was being chewed up,” Ludlam said. “I wouldn’t have thought much about it, except for the fact that I’ve been spending quite a bit of time recently around people that who are actually surveilled.”

Under the Telecommunications Interceptions and Access Act, dozens of state and federal government agencies are able to apply to access meta-data from mobile phones, including their precise GPS location.

Saturday’s Trades Hall conference opened with an audio address from Assange. WikiLeaks has been under serious scrutiny from ASIO ever since the US government alerted Australia of an imminent dump of military cables in late 2010.

On Twitter, Appelbaum suggested programs such as FinFisher or HackingTeam could have been sicced onto Ludlam’s phone to remotely access its microphone capacity and broadcast the audio to government spooks.

Appelbaum told the conference Senator Ludlam’s phone had an “interesting short battery life” since he had arrived in the country. Later he tweeted: “The good senator’s phone battery life went from reasonable to zero after visiting #LCA2012 with me. Many others, same issue.”

“I don’t want to come across as paranoid and delusional but Jacob is under regular surveillance and so is Julian Assange and his colleagues,” Ludlam explained. “Anyone with a smart phone, these things are used to track your location … not just by cell tower but also they’re reporting latitude and longitude by the GPS … these things can happen and it’s not necessarily your government doing it. ”

A straw poll conducted by fellow panellist and Assange co-author Suelette Dreyfus asked whether anyone at Trades Hall was a member of the intelligence or law enforcement community but it turned up no hands (Crikey‘s Bernard Keane was also at the forum discussing his e-book The War on the Internet). Repeated references were made to undercover ASIO officers in the audience and Dreyfus equated their “covert” activity with the Stasi.

The usual “casual clothes” get-ups worn by Melbourne-based ASIO officers familiar to activists include conspicuous English Premier League jerseys, however none were immediately evident in the auditorium.

So-called “warrant-less” wiretapping by Australian government agencies has exploded in popularity in recent years. In 2010-11, a record 243,631 applications for access so-called telecommunications “meta-data”, including IP addresses, the precise location of mobile devices and the identity of persons contacted, according to the Telecommunications Interceptions and Access Act annual report on the Attorney-General’s website.

Higher levels of interception used to access live data that permit listening in to phone calls and reading emails were less common, but still prevalent.

Ludlam, the Greens’ communications spokesman, told Crikey that meta-data requests were “fast becoming ubiquitous and very few people are aware of how widespread it is”,

Recently, federal Resources and Energy Minister Martin Ferguson requested souped-up surveillance by the Australian Federal Police on environmental activists using the outsourced skills of the National Open Source Intelligence Centre, which monitors blogs, Facebook and Twitter chatter.

ASIO told Crikey this morning that for “security reasons it would be inappropriate for ASIO to comment publicly on specific individuals”.

“However, it should be emphasised that ASIO’s collection of intelligence via telecommunications interception requires a warrant. ASIO must seek agreement from the Attorney-General and satisfy strict tests set out in relevant legislation before a warrant will be issued. ASIO’s warranted activities are the subject of particularly stringent oversight within ASIO and are regularly scrutinised by the Inspector-General of Intelligence and Security (IGIS).”