Award-winning director Paul Greengrass, whose credits include "The Bourne Ultimatum" and "United 93," said on Monday Britain needed to do more to nurture its young film-making talent.

Greengrass, who was nominated for an Oscar in 2007 for "United 93" - the story of passengers' unsuccessful attempt to wrest control of an airliner from hijackers on September 11, 2001 - said Britain had never been stronger in terms of directing talent but this position was under threat.

"No one is attending to what it's like to be a young director in this country at the moment," he told an audience at the Hay Festival. "It is going to have a catastrophic impact in five to 10 years time."

Greengrass, 52, who is know for his signature use of hand-held cameras, said film-making should be taught in schools as new technology had made it possible.

Fans shadowing him as he filmed action sequences of "The Bourne Ultimatum" had uploaded their own cuts caught on mobile phones before he had finished production, he said.

Greengrass began his film-making career in current affairs television, making a series of hard-hitting drama-documentaries.

These included "The Murder of Stephen Lawrence," about the racist killing of a black London teenager, and "Bloody Sunday," on the 1972 killing of 14 civil right marchers by British troops in Northern Ireland.

It was after "Bloody Sunday" in 2002 that Greengrass was hired to direct the thriller "The Bourne Supremacy," released in 2004, as a sequel to the first in the series, "The Bourne Identity," in which actor Matt Damon plays amnesiac spy Jason Bourne.

Geengrass is due to team up again with Damon for a fourth Bourne movie but no release date has yet been announced.