Stormtroopers join Prince William, Harry at The Last Jedi's London premiere

Prince William and Prince Harry joined the cast of Star Wars: The Last Jediat the film's European premiere Tuesday, delighting fans who braved the London cold for a glimpse of Hollywood stars and British royalty.

But cast and crew were silent on reports that the royal siblings make a cameo appearance in the much-anticipated film.

The tuxedo-clad princes walked the red carpet at London's Royal Albert Hall for the black-tie gala, a benefit for their Royal Foundation charity though without William's pregnant wife Kate or Harry's fiance, actress Meghan Markle.

Royal officials have refused to comment on reports that the princes recorded a scene playing Stormtroopers in the sci-fi saga when they visited the film's set in April 2016. At the time they were filmed meeting crew members, battling with light sabers and hugging a Wookie.

Star John Boyega has said the royal duo filmed a scene during their visit to London's Pinewood Studios, though it's unclear whether it made the final cut.

Cast members on the red carpet at London's Royal Albert Hall pleaded ignorance, and director Rian Johnson would not comment on the reported royal cameo.

"I can neither confirm nor deny it," he said.

London-born star Boyega was joined on the red carpet by fellow cast members including Daisy Ridley, Adam Driver, Andy Serkis, Kelly Marie Tran, Laura Dern,Benicio del Toro, Anthony Daniels who has played C-3PO in the Star Warsseries since 1977 and Mark Hamill, who returns as Luke Skywalker.

Hours before the screening, hundreds of fans lined up on one of the coldest days of the year for a glimpse of the stars, the royals and a phalanx of Stormtroopers who marched in formation up the red carpet.

"You never get used to this kind of passion and enthusiasm," Hamill said. "It's just wonderful. The fans have been so supportive over the years. Their enthusiasm is infectious."

The eighth film in the Star Warsseries, The Last Jedihad its world premiere Sunday in Los Angeles. The adventure is a follow-up to The Force Awakens,which brought the franchise back to movie screens in 2015.

It is the last film to feature Carrie Fisher as Princess Leia. Fisher died in December 2016 at 60, shortly after completing her final scenes.

Hamill said fans were helping him get through his sadness at Fisher's death.

"I shouldn't be upset she's not around, I should be grateful for all the time I had with her," he said.

"She was hilarious, adorable, [and]as tough as she acted, she had a vulnerability."

"She was so much fun. You're going to love her tonight, she's great in the film!" he added.