ET, released in 1982, won four Oscars

The screening was enhanced by a live soundtrack from a 100-piece orchestra, conducted by the soundtrack's composer John Williams.

Also present were Arnold Schwarzenegger and his wife Maria Shriver, Neve Campbell, Melissa Etheridge and child actors Haley Joel Osment and Dakota Fanning.

Spielberg said: "I never wanted to make a sequel to ET, but I thought it would be great to reissue the film on the 20th anniversary with a few enhancements to please the perfectionist inside myself, and for an audience both old and new."

The changes introduced by the director include new scenes, digitally-engineered changes to some of the film's famous shots and a remixed soundtrack.

Guns

More than 140 shots were reworked or, in some cases, filmed again.

Spielberg has also used digital technology to remove guns from the hands of the police following ET, Elliott and his friends during the film's climactic chase sequence.

Spielberg said that once he had children of his own, he "began to feel that the guns were probably an inappropriate thing to have in the movie, and felt that the 20th anniversary version was a great opportunity to get rid of them".

Peter Coyote, who was in the film, also attended

Digital artists "removed" the weapons guns and replaced them with walkie-talkies.

One of the movie's most memorable shots, of Elliot's flying bicycle silhouetted by the moon, was also reshot with a child replacing a figurine used in the original version.

"What worked in 1982 doesn't quite hold up," said Bill George, who supervised the updated special effects for Industrial Light & Magic.

And a bathroom scene featuring ET and Elliott - originally deleted - was reinstated and the range of ET's facial expressions widened.

ET: The Extra Terrestrial was originally released in June 1982, and after receiving nine Oscar nominations it won four.

The film opens in US cinemas on Friday and in the UK later in March.