Trevor Milton, chief executive of electric and hydrogen-powered truck start-up Nikola Motor Company, has resigned amid claims the company made fraudulent claims about its technology.

The resignation comes just two weeks after Nikola signed a $2bn (£1.6bn) partnership with General Motors.

Nikola also has a joint venture with Iveco to produce an electric truck. The deal saw Iveco invest $250m in the joint venture in September last year.

Milton’s departure follows a report from hedge fund firm Hindenburg Research earlier this month which claimed the company's success was “an intricate fraud” based on “an ocean of lies” including a video of a truck rolling downhill to give the impression it was cruising on a highway, and stencilling the words “hydrogen electric” on the side of a vehicle that was actually powered by natural gas.

Nikola Motor Company confirmed this week that Milton has resigned. Both Nikola and Milton refute all claims made about its vehicles.

Trevor Milton

In a message to employees Milton said he was stepping aside because “the focus should be on the company and its world-changing mission, not me.”

Nikola has said it will be taking legal action. It stated that the Hindenburg report is “replete with misleading information and salacious accusations directed at our founder and chairman.”

Referring to Hindenburg Research’s reputation for short-selling Nikola added that the start-up has been 'vetted by some of the world's most credible companies and investors.

“We are on a path to success and will not waver based on a report filled with misleading information attempting to manipulate our stock.”

Milton is succeeded by Stephen Girsky, a former General Motors executive who was already on the company’s board.

Nikola’s partnership with General Motors sees the car maker take an 11% ownership stake in Nikola. The deal includes plans to build Nikola’s Badger hydrogen fuel cell and electric pickup truck.

In December last year Trevor Milton told that OEM truck manufacturers were “arrogant”, accusing them of putting the brakes on the switch to zero emissions and warned that the days of diesel are “dying pretty quick”.