A “panic button” that erases mobile phone address books and sends emergency alerts is being developed in the US, which would be of help to pro-democracy campaigners.

The special application can be activated if the smartphone is confiscated by security authorities.

The US State Department is targeting countries ranging from the Middle East to China with the technology, according to a Daily Mail report.

It wants to equip the activists with the tools to fight back against repressive governments, the report said.

Michael Posner, US assistant secretary of state for human rights and labour, was quoted as saying: “We’ve been trying to keep below the radar on this, because a lot of the people we are working with are operating in very sensitive environments.”

The initiative is part of Secretary of State Hillary Clinton’s push to expand Internet freedoms, because of the crucial role social networking sites like the Facebook and Twitter has had in fuelling pro-democracy movements in Iran, Egypt, Tunisia and elsewhere.

The protesters in Cairo’s Tahrir Square underscored how important cell phones were to modern grassroots political movements, said Posner.

Posner added: “We are looking for the most innovative people who are going to tailor their technology and their expertise to the particular community of people we’re trying to protect.”

Since then it has viewed new media technologies as a key part of its global strategy, facing off with China over censorship of Google and launching its own Twitter feeds in Arabic, Farsi and Hindi.

The US has funded training for some 5,000 activists worldwide on the new technologies, and some sessions have turned up with surprises.

At a recent training session in Beirut, experts examined the computer of a Tunisian activist and discovered it was infected with “key-logging” software that could communicate what he was typing — presumably to security agents.