Lanky British actor Richard Armitage refused to unpack his bags for three weeks after flying out to New Zealand to play a dwarf in The Hobbit - because he was convinced Peter Jackson would fire him once the director realized how tall he was.

The filmmaker cast Armitage as Thorin Oakenshield, the king of the dwarves in Middle Earth, but the 41 year old, who stands tall at six foot, two inches (1.88 metres), was sure he would be promptly dismissed from the franchise and sent back to England at the start of the 18-month shoot.

He tells the Today show, "I thought I might be going on a plane home. I just figured that being six foot, two (inches) and taking on The Hobbit in that (dwarf) character (I would be released from the cast)."

However, Jackson had no problem with Armitage's height as he planned to use special effects to 'shrink' the actors onscreen, and instead he sent his cast of dwarves away to a boot camp to learn how to walk like little people.

And Armitage reveals they perfected the movements of a dwarf by wearing a specially-weighted belt.

He explains, "Luckily we had this strange dwarf boot camp... We had these belts that were weighted low down which were sort of pulling your center of gravity low, and then trying to sprint with that... so there was a lot of physical work, a lot of training."

The Hobbit: An Unexpected Journey, the first of three films based on the book by J.R.R. Tolkien, will hit screens this month (Dec12), with the subsequent two installments of the trilogy set for release in 2013 and 2014.