Leonard Nimoy continually fought back tears on the set of the sci-fi franchise's new movie - because he couldn't help but recall dead pals and castmates.

The original Mr. Spock reprises his unemotional Vulcan role in the new J.J. Abrams' film and admits he was all emotion as he watched characters from the beloved 1960s Star Trek TV series meeting for the first time in the new prequel.

And there was one scene he really struggled with - when Captain Kirk, played by Chris Pine, met Karl Urban's Dr. McCoy for the first time.

DeForest Kelley, who portrayed the original McCoy, was a longtime friend of Nimoy's, who died 10 years ago next month (Jun09).

Nimoy tells America's TV Guide magazine, "I started crying - and it (scene) still moves me now. I loved D-Kelley, salt of the earth.

"I cried a lot watching this production."

J.J. Abrams' re-working of the popular sc-fi franchise see the story go back to the beginning with the maiden voyage of the Enterprise.