Palo Alto, California - Tesla will only accept Bitcoin payments again if the cryptocurrency significantly cleans up its production processes to reduce environmental damage, according to Elon Musk.

Around 50% clean energy usage in Bitcoin production would be an acceptable benchmark, Musk tweeted on Sunday.

Bitcoin is generated through complex computing processes that require huge amounts of electricity. Cryptocurrencies have drawn criticism from climate advocates for this reason.

Musk and Tesla have made several announcements about Bitcoin in recent months that have caused the value of the currency to fluctuate. Musk was also the recent recipient of a video warning from hacker group Anonymous, who accused him of intentionally manipulating the value of Bitcoin.

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First, the firm announced it had invested some $1.5 billion into Bitcoin and would soon allow customers to pay for their Tesla cars using the digital currency.

Bitcoin was introduced as a payment option in March, but put on hold again after less than two months, with Musk citing Bitcoin's poor environmental record.

On Twitter, Musk gaming the price of Bitcoin with his frequent changes of course.

Musk said Tesla had sold around 10% of its Bitcoin holdings to prove they could be dumped without significantly shifting the cryptocurrency's price. However, just in response to his tweet, the value of Bitcoin jumped again over the weekend.