Harrison thought ASIO might want to talk to her about her involvement with Quit Coal, but the the security officers said they wanted to discuss the ''anarchist scene'' in Melbourne. They said they were talking to ''lots of people'' in an effort to understand anarchist viewpoints. Broadly defined as a political philosophy that opposes authority or hierarchical organisation in social and political life, anarchism has become more popular in the past decade as part of the international anti-war, anti-capitalist and anti-globalisation movements. Anarchists were active in the demonstrations and riots that accompanied the G20 finance ministers' meeting in Melbourne in November 2006, and Harrison says ASIO asked her whether there was any support among Australian anarchists for violence as a means to achieve political goals. They were also ''very curious'' about connections between Australian anarchists and similar groups overseas. But the ASIO officers had one specific case they wanted to talk about. They asked Harrison what she knew about Felicity Ann Ryder, another Melbourne activist who had attracted brief media attention in early July. They showed Harrison a couple of news articles about Ryder and asked what she thought about her activities. The daughter of Lyndon and Jenny Ryder, a couple who run businesses in the Victorian town of Rutherglen, Felicity Ryder is a Melbourne University politics and history graduate who has at least five years' experience as an activist in the anarchist movement. Her interests include animal liberation and environmental protest, and involvement with Barricade, an anarchist bookshop and information centre.

Other Melbourne-based activists describe Ryder as ''quiet, and quite serious'', ''not someone who drew attention to herself'' and '' a typical young activist [who was] active in a general sense but didn't stand out''. A talented linguist, Ryder has travelled widely and is understood to have worked in the Israeli-occupied West Bank. Her political activities remained low profile until early July this year when media reports from Mexico linked her with an alleged anarchist bomber in Mexico. The bomber, Mario Antonio Lopez Hernandez, was arrested by police on June 27 after he was seriously injured when he accidentally detonated an improvised explosive device on a street in the Coyoacan district of Mexico City. Mexico has a long anarchist political tradition that was given new inspiration by the Zapatista rebellion in Chiapas state in 1994. Anarchist students at the National Autonomous University of Mexico in Mexico City led campaigns against tuition fee rises and Mexican anarchists were prominent in the protests that accompanied the 1999 Seattle meeting of the World Trade Organisation. A series of anarchist bombings took place in Mexico City in 2006 and petroleum pipelines in central Mexico were targeted in 2007. Over the past 18 months so-called ''eco-anarchists'' have also targeted Mexico's growing nano-technology sector with a letter-bomb campaign apparently modelled on the ''Unabomber'' attacks of Theodore Kaczynski in the US.

Hernandez is accused of a bombing outside a Mexican Federal Electricity Commission in Tlalpan in June and of planning at least one other explosion. Mexican police allege that Hernandez declared himself an anarchist, a fighter for ''Total Liberation'', and admitted that he used the internet to research how to build the bombs. Ryder was immediately linked to Hernandez when her passport was found in his backpack. The Australian activist had arrived in Mexico last December and reportedly met Hernandez through the internet. In early July Mexican media reported that Ryder had been arrested. This was dramatic news for her parents who were bombarded with media inquiries. However, while the Department of Foreign Affairs and Trade indicated it was aware Ryder was wanted by Mexican authorities, there was no confirmation of her arrest and no request for consular assistance was made. Ryder's whereabouts were unknown, including to her parents, and in the absence of new information, Australian media interest quickly faded. But in a statement posted on the Mexican anarchist website Liberacion Total two weeks later, Ryder confirmed that she hadn't been arrested and expressed her thanks to ''everyone who has worried about me and my situation, to those who have shown solidarity with Mario and I''. Ryder accused the Mexican police of spreading false reports of her arrest. ''If it was to try in vain to break or manipulate Mario, to manipulate my family, or to try to appear half confident in doing their jobs, I don't know,'' she wrote.

''What I do know is that I am proud of being an anarchist, and proud to be an enemy of authority and the state.'' Hernandez, under guard in hospital while his wounds healed, released a statement in which he took responsibility for his actions and denied Ryder's involvement in the bombings. He said ''the problem is that [she] is now implicated'' because they left a backpack at the scene of the attempted bombing and her ID was in it. She was also identified in video recorded by street cameras. Hernandez and Ryder are now heroes for anarchist extremists around the world. In October nine Greek anarchists, members of an ''urban guerilla'' group Conspiracy of Cells of Fire on trial for bombings in Athens, issued a statement that declared ''with our thoughts and hearts, we stand close to anarchist comrade Mario Lopez … and anarchist Felicity Ryder, who chose the clandestine paths and is prosecuted for the same case''. Jenny Ryder has told Fairfax Media that it was ''beyond comprehension to think that our daughter would have had any involvement with violence. ''We as her parents, and her family, have the utmost respect for her beliefs, her commitment to social justice that we know is very close to her heart.''

Whatever the details of Ryder's association with Hernandez, she is clearly regarded by security authorities in Mexico and Australia as a ''person of interest'' in relation to terrorist bombings. Fairfax Media has confirmed that ASIO has pursued a wide-ranging investigation in relation to Ryder, including ASIO officers carrying out inquiries in her home town of Rutherglen. ASIO liaises with its Mexican counterpart, the Centre for Research and National Security (Centro de Investigacion y Seguridad Nacional) and the Australian security agency's inquiries have focused on identifying friends and associates whom Ryder might contact. Ryder has been in intermittent email contact to advise friends and family that she is safe. However, she has not disclosed her whereabouts and has indicated that, on legal advice, she does not intend to present herself to Mexican authorities soon. A warrant has been issued for her arrest by the Mexico City attorney-general and Mexican border security has been alerted. Rebecca Harrison says she couldn't tell ASIO officers anything about Ryder because as far as she could recall, she'd never met her and her own knowledge didn't extend beyond what was in the news articles that they showed her at Kafe Mument. Significantly, however, the ASIO officers were also keen to inquire broadly about the Melbourne anarchist scene, asking who the main leaders and identities were, and what they thought about violent protest. After asking whether there would be any ''solidarity events'' organised in support of Ryder, the ASIO officers said they would be ''very interested'' to learn who organised or attended any such gatherings. Harrison says she told ASIO she knew of no evidence of any inclinations towards violence among Melbourne's anarchist groups.

Anarchist extremists have certainly become a focus for law enforcement and security agencies in Europe and North America. In February, the FBI arrested five self-described anarchists for allegedly plotting to blow up a bridge in Cleveland on May Day. Federal Attorney-General Nicola Roxon briefly referred to anarchists as a threat when she was asked on the ABC's Q&A program in April about reports in Fairfax Media about federal police and ASIO interest in environmental activists and anti-coal protesters. ''Peaceful protest is one thing, and sometimes peaceful protest can break the law,'' Roxon said, ''but there is also a lot of industrial sabotage, which gets to a point where it is actually the commission of quite a serious crime,'' she said. ''Unfortunately we do see a growing number of links across some sorts of groups who are anarchist … and intent with committing a terrorist offence that might link in with other protest groups.'' Security sources have told Fairfax Media that international connections between anarchist extremists, facilitated by the internet, are ''a matter of legitimate concern'' and that ''radicalisation'' through contact with overseas extremists is ''something that has to be monitored''.

Of particular interest is Australian activist engagement in the potential development of ''Deep Green resistance'', inspired by the writings of American ''anarcho-primitivist'' theorist Derrick Jensen, including the formation of a militant ''underground'' engaged in direct action against economic and energy infrastructure. Australia's hosting of the G20 economic leaders' meeting in Brisbane in November 2014, together with related gatherings in other state capitals, is raised as a particular focus for security planning. ''These international economic meetings are a traditional focus for anarchist extremists,'' a senior law enforcement official said. ''In order to know what the threats might be in 2014, we need to adjust intelligence priorities and open inquiries now.'' Melbourne's anarchist circles can probably expect more telephone calls from ASIO like that received by Rebecca Harrison, and plenty of surveillance they won't ever know about. Loading

Meanwhile, somewhere in Mexico, Felicity Ryder remains at large - a high-priority counter-terrorism target. Philip Dorling is a senior writer.