Young Eritreans, who have fled abroad to escape their government’s stifling repression and years of compulsory military service, have turned to new media to attack the regime. Over the last year they have used chat-rooms, phone messaging and flash-mobs to get their message across.

In the last decade, tens of thousands of Eritreans slipped across their country’s heavily guarded borders. After surviving shipwreck in the Mediterranean or banditry, torture and extortion in the Sinai, they are building new lives in Europe, the US and Israel. Many are deeply angry that they have had to flee from their homeland, and looking for a means of attacking President Isaias Afwerki grip on power. But Eritrea is – after North Korea – probably the most inaccessible of regimes. It accepts almost no foreign aid, has expelled most United Nations agencies and forbids foreign ambassadors from travelling outside the capital, Asmara.

Since the early 1990s, all independent media have been silenced, critics jailed and the university closed. Isolated in exile, young Eritreans have developed new forms of resistance through a campaign group, Eritrean Youth Solidarity for Change.

They began with phone numbers smuggled out of the country. Eritrean towns and villages were targeted for phone calls at random. "We wanted to show Eritreans that they were not isolated," explained Selam Kidane, one of the London organisers. "At first people were very frightened, but gradually that has faded," Selam told me. "Now, when I get through I get passed from person to person."

Next the group turned to robocalls to spread their message. Automated messages recorded by a priest for use on 29 November, the feast of Saint Mary. Five thousand calls were made, urging people to go to St Mary’s church in Asmara, to commemorate the disappearance in 2005 of the Patriach of the Eritrean Orthodox Church, Patriach Abune Antonios. The organisers claim that around 5,000 of the 6,800 calls got through. Some were followed up by one to one conversations.

Since then there have been a series of concerted campaigns, focussing on smaller towns. The organising group, called Arbi Harnet or ‘Freedom Friday’, asks Eritreans to remain off the streets, as a mark of solidarity. "The main objective is to penetrate the government’s iron curtain, to reach our people and encourage them to take communal action and link the resistance," says Ahmed Abdelrahim from Melbourne, a singer and song writer who co-founded Arbi Harnet.

Other calls have been used to mark particular events. This month, the ninth anniversary of the detention of Astern Yohannes, a guerrilla fighter was marked with 10,000 calls. She is also the wife of one of Eritrea’s best known imprisoned politician and first minister of defence, Petros Solomon. A video has been produced, explaining how she returned home in December 2003, after studying for three years at University of Phoenix in Arizona, to be with her children. Posters have been sent over the internet, describing the plight of young Eritreans who become held to ransom in the Sinai by people smugglers. Some have been secretly put up in Asmara and covertly filmed on mobile phones.

But perhaps the most powerful weapon has been through chat-rooms like Paltalk. This has enabled young exiles, the majority of whom have few foreign languages and no experience of the outside world, to escape their isolation. Together they have become what they call "the team that never sleeps." Living across the globe, with members in Australia, Europe and California, they plan and co-ordinate their operations. Flash mobs from Switzerland to Scotland have broken up meetings organised by government supporters, and the Eritrean ambassadors now have few opportunities to openly push the official line.

Unlike the first generation of exiled Eritreans, who concentrated on formal organisational structures, the youth are keen to act rather than plot and plan. With no formal structure and no borders, these young men and women are challenging a regime that has been described by Human Rights Watch as one of the most repressive in the world.

Martin Plaut is a senior research fellow at the Institute of Commonwealth Studies