Margaret Atwood will highlight the work of persecuted authors

More than 500 authors will be involved in 650 events in Charlotte Square Gardens between Saturday and 29 August.

The big names include Zadie Smith, John Irving, Julian Barnes, Tony Benn and television news men Jon Snow, Fergal Keane, Andrew Marr and Rageh Omaar.

The festival will also look at the shape of nations in the 21st Century.

This year's event sees the launch of the Nations Unlimited series, which has been planned in collaboration with festivals in Norway and Sweden.

Edinburgh is now the world's first Unesco City of Literature, in recognition of the deep and dynamic role literature plays in this land Catherine Lockerbie Festival director

Novelists, poets, journalists, scientists, historians, biographers and illustrators from 30 different nationalities will take part in the festival, including a record 170 Scots.

Mr Rushdie, who is about to publish his new novel Shalimar the Clown, is making his first appearance at the event in two decades.

Book festival director Catherine Lockerbie said: "Edinburgh is now the world's first Unesco City of Literature, in recognition of the deep and dynamic role literature plays in this land.

"We are delighted to be reinforcing this message by bringing titans of world literature to the capital."

She said the imprisoned writers series was "a distinctive and vital" part of the festival.

Salman Rushdie last appeared at the festival 20 years ago

Margaret Atwood and Iain Banks are among the authors who will take part in readings to show solidarity with persecuted poets, journalists and polemicists.

The series will be opened on Saturday by celebrated Zimbabwean author Chenjerai Hove.

Amnesty International's Rosemary Burnett said: "The wholehearted support of top book festival authors for these sessions is inspiring.

"Their readings will highlight, in a really accessible and moving way, the work of writers who have been murdered, tortured, imprisoned or persecuted, banned, censored or exiled - all for merely expressing their views.