A "final effort" is under way in South America to track down and prosecute ex-Nazi war criminals before they die.

Operation Last Chance - a scheme devised by the Simon Wiesenthal Center - attempts to locate Nazis in hiding.

It takes the form of a media campaign and offers financial rewards for any information that results in conviction.

The four countries involved are Chile, Uruguay, Argentina and Brazil - where large numbers of Nazis are thought to have fled following World War II.