Elon Musk acknowledged the mission's failure, posting on X that "success is uncertain, but entertainment is guaranteed."

SpaceX's Starship spacecraft broke apart mid-flight, forcing airlines to change flights to avoid falling debris.

While Elon Musk's company successfully repeated its previous feat of capturing a first-stage booster when it returned to Earth on Thursday, its new generation of unmanned spacecraft was lost.

The U.S. Federal Aviation Administration (FAA) "briefly" slowed the plane and changed its course around the area where debris fell from the spacecraft, the aviation regulator said.

"Normal operations have resumed," a spokesman said.

At least 20 flights changed course to avoid potential debris, according to flight tracking website FlightRadar24, as videos on social media appeared to show part of the craft re-entering the atmosphere in the Caribbean.

Musk said the spacecraft's disintegration appeared to be caused by an oxygen or fuel leak in the cavity above the ship's engine firewall.

Musk posted on his social media platform Launch postponed to next month."

Musk earlier admitted the mission failed and released footage of falling debris.

"Success is uncertain, but entertainment is guaranteed!" he said.

About eight and a half minutes after the prototype took off from the launch site near Brownsville, Texas, SpaceX ground control lost contact with the prototype.

The vehicle, which is flying for the first time, carries 10 virtual satellites and is expected to complete part of its orbit around the Earth.

"Starship experienced a rapid, unscheduled breakup during ascent," the company said in a post on X.

"The team will continue to review the data from today's flight test to better understand the root cause. Success comes from what we learn through tests like this, and today's flight will help us improve the reliability of Starship."

The mission is the seventh test flight of SpaceX's Starship, which Musk expects will one day carry people and cargo to Mars.

Earlier Thursday, Jeff Bezos' Blue Origin successfully launched its New Glenn rocket into orbit for the first time, marking a milestone in the race for commercial space travel.

In a series of X posts after Blue Origin's launch, Musk likened his relationships with space industry rivals to those between Will Ferrell and John C. Wray in the 2008 comedy "Step Brothers." The relationship between the characters of John C Reilly.