Scientific progress is almost certain to bring disaster to planet Earth, top cosmologist Stephen Hawking says.

He predicts that as new technologies are developed, the number of threats to the human race will increase until some kind of global cataclysm is virtually inevitable.

Warning: Professor Stephen Hawking.

In the time period before humans manage to escape to the stars, they will have to be "very careful", he says.

Professor Hawking's warning came during a question and answer session at the BBC Reith Lectures at London's Royal Institution on January 7.