Tesla and SpaceX CEO Elon Musk has called Apple the "Tesla graveyard", alleging that many of the tech giant's senior staff are former Tesla employees who couldn't make it at his company.

Speaking to German paper Handelsblatt, Musk hit back at claims that many of his high-ranking staff were recruited by Apple.

He said: "We always jokingly call Apple the 'Tesla Graveyard.' If you don't make it at Tesla, you go work at Apple. I'm not kidding."

He also managed to put down the Apple Watch and the company's ambitions at creating an electric car in one fell swoop.

Laughing, he said: "Did you ever take a look at the Apple Watch?"

He continued: "No, seriously. It's good that Apple is moving and investing in this direction. But cars are very complex compared to phones or smartwatches. You can't just go to a supplier like Foxconn and say 'build me a car.'"

"But for Apple, the car is the next logical thing to finally offer a significant innovation. A new pencil or a bigger iPad alone were not relevant enough."

It was reported in September this year that Apple has 'committed' to making its own car with the codename 'Project Titan', which could be released as early as 2019 and would compete with Tesla's cars in the electric car market.

The reason that so many former Tesla employees work at Apple could be more complicated than Musk makes out, however.

In a 2012 interview with Autoblog, Musk proudly spoke of the long and difficult hours that Tesla employees are expected to work.

He said: "If you work for Tesla, the minimum is really a 50-hour week and there are times when it'll be 60-to-80 hour weeks."

"If somebody is hourly, they receive time-and-a-half but if somebody is salary, then we do cash and stock bonuses for going above and beyond the call of duty. So we try to make it fair compensation, but the general understanding is that if you're at Tesla, you're choosing to be at the equivalent of Special Forces."

"There's the regular Army, and that's fine, but if you are working at Tesla, you're choosing to step up your game."

Musk has previously accused Apple of trying to poach Tesla staff, in a February interview with Bloomberg Businessweek.