A Japanese billionaire arrived at the International Space Station on Wednesday, marking Russia's return to space tourism after a decade-long pause that saw the rise of competition from the United States.

Online fashion tycoon Yusaku Maezawa and his assistant Yozo Hirano blasted off from the Baikonur cosmodrome in Kazakhstan earlier on Wednesday.

They docked with the Poisk module of the Russian segment of the ISS at 1340 GMT, the Russian space agency said.

A Roscosmos livefeed showed the hatch of the Soyuz MS-20 capsule open at 1611 GMT, showing Russian cosmonaut Alexander Misurkin entering the ISS, followed by Maezawa and Hirano.

Their journey aboard the three-person Soyuz spacecraft piloted by Misurkin took just over six hours, capping a banner year that many have seen as a turning point for private space travel.

As the hatches opened, the trio floated into the orbital station where they were greeted by Russian cosmonauts Anton Shkaplerov and Petr Dubrov.

The station is currently home to an international crew of seven people.

Billionaires Elon Musk, Jeff Bezos and Richard Branson all made breakthrough commercial tourism flights this year, bursting into a market Russia is keen to defend.

A crowd at the launch site -- including Maezawa's family and friends -- braved freezing temperatures and cheered as the rocket blasted off into the grey sky, leaving a trail of orange flames before disappearing in the clouds.

"This has been a long process. It's so moving. I was about to cry," said Ryo Okubo, a lawyer for Maezawa's space projects.

"I'm really excited but he's also my friend so I'm worried about him," a longtime friend of the billionaire, 44-year-old Hiroyuki Sugimoto, told AFP.

The trio will spend 12 days on the station where the Japanese tourists will document their daily life aboard the ISS for Maezawa's popular YouTube channel.

The 46-year-old billionaire has set out 100 tasks to complete onboard, including hosting a badminton tournament.

Maezawa also plans to take eight people with him on a 2023 mission around the moon operated by Musk's SpaceX.

He and his assistant are the first private Japanese citizens to visit space since journalist Toyohiro Akiyama travelled to the Mir station in 1990.

Russia has a history of shepherding self-funded tourists to space.

In partnership with US-based company Space Adventures, Roscosmos previously took seven tourists to the ISS since 2001 -- one of them twice.

 'Very patient and creative'

The last was Canada's Cirque du Soleil co-founder Guy Laliberte in 2009, who was dubbed the first clown in space.

Tom Shelley, president of Space Adventures, praised Russia's return to the booming space tourism business.

"It's been 12 years. We've had to be very patient. We've had to be very creative. So, this is the culmination of a lot of effort from a lot of different people," he told AFP shortly after liftoff.

In October, Russia launched its first untrained cosmonauts into space since Laliberte's trip, delivering a Russian actress and director to the ISS where they filmed scenes for the first movie in orbit.

Moscow had stopped sending tourists to space after NASA retired its Space Shuttle in 2011, which left Russia with a monopoly on supplying the ISS.

NASA bought up all Soyuz launch seats for a reported $90 million per spot -- effectively ending tourist flights.

That changed last year when a SpaceX spacecraft successfully delivered its first astronauts to the ISS.

NASA began purchasing flights from SpaceX, stripping Russia of its monopoly and costing its cash-strapped space agency millions of dollars in revenue.

While the cost of tickets to space for tourists has not been disclosed, Space Adventures has indicated that they are in the range of $50-60 million.

Roscosmos plans to continue growing its space tourism business, already commissioning two Soyuz rockets for such trips.

"We will not give away this niche to the Americans. We are ready to fight for it," Roscosmos director Dmitry Rogozin said after the launch.

He told reporters that Russia has received two applications for future space flights and a group of potential travellers is already working at the cosmonaut training centre.

"I can say that this is a Russian group," he added.