A top secret US spy satellite is believed to have been totally destroyed after a botched launch on Elon Musk's SpaceX.

The Wall Street Journal is reporting that US politicians had been briefed about the apparent destruction of the secretive payload — codenamed Zuma — burned up in the atmosphere after failing to separate from the upper part of the rocket.

The wrecked satellite is worth billions of dollars.

A SpaceX spokesman told the Dow Jones news service: "We do not comment on missions of this nature, but as of right now reviews of the data indicate Falcon 9 performed nominally."

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The Zuma spacecraft was attached to one of SpaceX's Falcon 9 rockets and launched from the Cape Canaveral Air Force Station in Florida. The Falcon 9 returned back to base without incident.

Landing and reusing rockets is the main aim of SpaceX scientists, who argue that it reduces the cost of launches that would then allow them to fly more missions.

The mission was the first Elon Musk's Space X had attempted this year. It plans to launch as many as 25 by the end of 2018, up from 18 last year.