Watch: SpaceX Starship, world's biggest rocket, explodes during first flight test

SpaceX's Starship, the most powerful rocket ever built, exploded on Thursday during the first test flight of the spacecraft designed to send astronauts to the Moon, Mars and beyond.

The gigantic rocket successfully blasted off at 8:33 am Central Time (1333 GMT) from Starbase, the private SpaceX spaceport in Boca Chica, Texas.

The Starship capsule had been scheduled to separate from the first-stage rocket booster three minutes into the uncrewed flight but separation failed to occur and the rocket blew up.

"As if the flight test was not exciting enough, Starship experienced a rapid unscheduled disassembly before stage separation," SpaceX tweeted.

Despite the failure to complete the full flight test, SpaceX declared it a success.

"We cleared the tower which was our only hope," said Kate Tice, a SpaceX quality systems engineer.

"With a test like this, success comes from what we learn, and today’s test will help us improve Starship’s reliability as SpaceX seeks to make life multi-planetary," SpaceX tweeted.

The US space agency NASA has picked the Starship spacecraft to ferry astronauts to the Moon in late 2025 -- a mission known as Artemis III -- for the first time since the Apollo program ended in 1972.

Starship consists of a 164-foot (50-meter) tall spacecraft designed to carry crew and cargo that sits atop a 230-foot tall first-stage Super Heavy booster rocket.

SpaceX conducted a successful test-firing of the 33 massive Raptor engines on the first-stage booster in February but the Starship spacecraft and the Super Heavy rocket were being flown together for the first time.

The integrated test flight was intended to assess their performance in combination.

SpaceX founder Elon Musk had warned ahead of the launch that technical issues were likely and sought to play down expectations for the inaugural test flight.

"It's a very risky flight," he said. "It's the first launch of a very complicated, gigantic rocket.

"There's a million ways this rocket could fail," Musk said.