San Francisco, Aug 27 (IANS): Tesla and SpaceX CEO Elon Musk on Saturday slammed some environmentalists for being "anti-human" when it comes to increasing nuclear power generation that could replace fossil fuels in the future.

In a tweet, Musk said that the countries should be increasing nuclear power generation.

"It is insane from a national security standpoint and bad for the environment to shut them down," said Musk.

A Twitter follower replied, saying that nuclear is clean, efficient and could replace fossil fuels entirely if it was embraced but is not happening "because so-called environmentalists aren't pro clean energy, they are anti-human".

Musk posted: "Some (environmentalists) are indeed sadly anti-human".

A clean energy advocate, he has said time and again that it's a mistake to stigmatise nuclear energy, especially as renewables like solar and batteries are still ramping up.

In July this year, he said that "I'm actually pro-nuclear as well".

"I think nuclear has a bad rap. People shouldn't be shutting down nuclear power stations, in my view, unless they're in a location that's prone to natural disasters. In which case, you know you can't just be like, 'we're just waiting for the real but once in a century situation'," he said during an interview on the 'Getting Stoned' podcast.

"Like the Fukushima situation. Well, you know there's a lot of tsunamis and stuff, so it's probably not great to have nuclear power where there's natural disasters. But for example, in places like France or Germany and many parts of the US, there's really no meaningful risk of a natural disaster that could affect nuclear power plants. So we shouldn't shut them down in that case," Musk had stressed.

According to him, efforts to shut down nuclear power plants are "crazy" and "madness."