Elon Musk's SpaceX is planning to fly private crew missions to the International Space Station in partnership with a Calfornia-based startup, the two companies said Thursday.

The missions are contingent on approval by NASA and involve the Vast startup, which also aims to launch the world's first commercial space station as early as next year.

"Enabling payload and crewed missions to the ISS is a key part of Vast's strategy, allowing us to further our collaboration with NASA and global space agencies," Vast's CEO Max Haot said in a statement, which did not provide a timeline.

SpaceX has previously flown three private missions to the orbital laboratory with Axiom Space and is preparing for a fourth.

It has also partnered with Polaris, a venture led by billionaire Jared Isaacman, for two orbital voyages, one of which featured the first spacewalk by non-professional astronauts.

Isaacman has been nominated by President-elect Donald Trump as the next NASA administrator, reflecting an era of expanding public-private partnerships in space.

"I am excited to work with Vast as they build more opportunities and destinations for more people to travel amongst the stars," said Gwynne Shotwell, SpaceX's president and chief operating officer.

Such missions cater to both wealthy individuals and sovereign governments.

The last Axiom mission included astronauts from Italy, Sweden and Turkey, whose seats were sponsored by their respective nations.

Vast also revealed that it is in active discussions with several governments, including the Czech Republic, about future missions.

With the ISS set to be decommissioned in 2030, Vast is among several companies competing to build and launch the world's first commercial space station.

Other contenders include Axiom Space, Voyager Space in partnership with Airbus, and Blue Origin in collaboration with Sierra Space.