More than 500 of the world's leading authors, including five Nobel prize winners, have condemned state surveillance as revealed by the whistle-blower Edward Snowden, according to today's edition of The Guardian newspaper. Through their petition to the UN, the writers - along with at least one well-known musician - warn that spy agencies are undermining democracy.

The signatories come from 81 different countries. They include Margaret Atwood, Don DeLillo, Orhan Pamuk, Günter Grass and Arundhati Roy and the musician and actress Björk.

Irish author Roddy Doyle is a signatory as are Julian Barnes, Martin Amis, Ian McEwan, Irvine Welsh, Hari Kunzru, Jeanette Winterson and Kazuo Ishiguro. Henning Mankell, Lionel Shriver, and Hanif Kureishi have also signed.

The signatories argue that the fact that intelligence agencies are spying on millions of people is turning everyone into potential suspects.

They have requested the United Nations to create an international bill of digital rights to guarantee the protection of civil rights in the internet age.