Sir Ian McKellen snubbed a starring role alongside Tom Cruise in 'Mission: Impossible II'.

Sir Ian McKellen

Sir Ian McKellen

The 76-year-old actor has admitted it was a huge risk turning down a role in the franchise but says he wouldn't have got his famous parts in 'The Lord of the Rings' and 'X-Men' if he had accepted.

He told PEOPLE magazine: "I got offered a part in 'Mission: Impossible II' with Tom Cruise, but they wouldn't let me see the whole script because I might have spilled the beans. I only got my scenes.

"Well, I couldn't judge from reading just those scenes what the script was like. So I said no. And my agent said, "You can't say no to working with Tom Cruise!" and I said, "I think I will.

"The next day, Bryan Singer asked me to play Magneto (in 2000's 'X-Men') and then Peter Jackson asked me to play Gandalf (in 'The Lord of the Rings'), and I said yes to both."

Meanwhile, Ian previously admitted he swiped a few of the "precious" props from the set of the fantasy film series.

He admitted: "And I think my favorite set, that I didn't act in, was the golden Liar, where the dragon was hiding. Hundreds of thousands of golden coins, specially made. And if you don't tell anyone, I can tell you that I have some of those coins.

"[I also have] the front door key to Bag End, which i know Peter Jackson is looking for, but will never find."