MONTREAL - The billionaire businessman behind Virgin Galactic says William Shatner -- and other celebrities -- shouldn't expect any free rides into space.

The space-tourism enterprise is already taking reservations for flights which could begin sometime next year.

But it's become clear that the actor who played Captain James T. Kirk, perhaps the world's most famous fictional spaceman, is not among the 440 people from 40 countries planning to go up.

"William Shatner has said that he's scared to go into space and it's quite ironic really when you think of his career," company founder Sir Richard Branson told The Canadian Press.

"And, like most celebrities, he would like a freebie."

The 80-year-old actor recently admitted he did not want to boldly go anywhere beyond the Earth's atmosphere.

"I'm scared," Shatner said after he was given an honorary doctorate at his alma mater, Montreal's McGill University.

Branson suggested the Star Trek actor is in the minority.

"Most people are unlike William Shatner," he added. "I would say nine out of 10 people -- if they could afford it -- would love to go into space."

Branson, who also has his hand in a number of airlines, says he won't be offering any deals.

"I'm in the airline business and a lot of people ask for upgrades and we're not going to get the same thing happening with our space program."

Branson says since Shatner isn't interested, perhaps other crew members of the fictional USS Enterprise, like "Spock" (aka Leonard Nimoy), would jump at the chance.

"We'll have to go out and ask them," he added. "We haven't actually yet, but I promise you we will."

The sub-orbital flights Virgin plans to offer would send a spaceship into space, without actually completing an orbit of the Earth.

After being launched from the mother ship, a two-piloted rocket plane would take six tourists about 110 kilometres above Earth -- where they would briefly experience weightlessness.

The cost of a seat is $US200,000.

Virgin Galactic has already taken deposits of just under $55 million. StarShipTwo, the mothership, is currently undergoing testing.

Shatner recently recalled that Branson had offered him a spot -- if he paid his way.

"I said, 'Well, that's not much, (but) how much do you guarantee to come back?' And he didn't have a price on that," Shatner quipped.

"He (Branson) wanted me to go up and pay for it and I said: 'Hey, you pay me and I'll go up. I'll risk my life for a large sum of money.' ... But he didn't pick me up on my offer."

It was widely reported in September 2006 that the Star Trek legend was offered a ticket by Branson aboard Virgin Galactic's first passenger flight, which was originally planned for 2008.

At the time, Shatner said he was worried about getting sick.

"I'm interested in man's march into the unknown but to vomit in space is not my idea of a good time. Neither is a fiery crash with the vomit hovering over me," he said at the time.