Fugitive whistleblower Edward Snowden has asked hackers across the globe to develop technologies to counter illegal surveillance by government agencies.

Addressing a hackers conference known as Hackers On Planet Earth (Hope) via video link from Moscow, Snowden said he intends to devote much of his time to promoting easy-to-use counter-surveillance technologies which allow people to communicate anonymously with a high level of encryption.

"You in this room, right now have both the means and the capability to improve the future by encoding our rights into programmes and protocols by which we rely every day," he told the conference, which included computer experts, anti-surveillance activists, artists and other types of hackers.

"That is what a lot of my future work is going to be involved in."

Snowden attracted international attention after he leaked up to 1.7 million top secret documents about the NSA's surveillance programmes.

The Obama administration faced severe criticism across the globe as the documents revealed that the NSA had tapped telephone conversations and spied on the internet activities of prominent people, including German chancellor Angela Merkel and Brazilian president Dilma Rousseff.

Snowden, who is currently in Russia, is wanted by the US on charges of espionage and theft of government property.

During his speech, Snowden did not say anything about his extended stay in Russia. He had earlier applied for extension of his temporary visa in Russia as he felt a return to the US and a fair treatment from authorities may not be possible.