Tesla boss Elon Musk is once again causing movement in cryptocurrencies via Twitter.

Bitcoin rose 9.8 percent on Sunday to $ 39,035, more than 40 percent above the annual low of $ 27,734 on January 4th.

The digital currency Ether climbed seven percent to $ 2,532.77.

Musk had previously announced that Tesla would again accept Bitcoin as a means of payment under certain conditions.

If it turns out that a reasonable share of around 50 percent renewable energies is used in Bitcoin production and there is also a positive trend in this direction, Tesla will again allow Bitcoin transactions, Musk tweeted on Sunday evening.

Bitcoin are created through complex arithmetic tasks on computers.

Large amounts of electricity are used in this process.

Environmentalists therefore criticize the digital currency as a climate killer.

Back and forth since March

Musk announced in March that Tesla would also sell its cars for Bitcoin in the future. In May he made a U-turn and justified this with climate concerns. Musk also tweeted on Sunday evening that Tesla had sold about ten percent of its Bitcoin holdings "to confirm that Bitcoin can simply be liquidated without moving the market."

Musk responded with his tweet to a post on the Internet service "Cointelegraph", which he rejected with the words "That does not apply". An interview with the head of the financial services provider Sygnia, Magda Wierzycka, was reproduced there. "What we saw with Bitcoin is the price manipulation by a very powerful and influential person," said Wierzycka there. There were market fluctuations in Bitcoin, which she would describe as "market manipulation by Elon Musk". If this happened to a publicly traded company, it would be investigated by the US Securities and Exchange Commission and severely punished. Musk knowingly increased the price of Bitcoin by, among other things, writing tweets mentioning that Tesla had bought $ 1.5 billion in Bitcoin, the Sygnia boss said.He then sold a large part of it at the height of the Bitcoin price.

Musk has been criticized by some market watchers for months. They accuse him of affecting the Bitcoin exchange rate with sometimes simple tweets and thereby giving themselves or Tesla the opportunity to gain financial advantages. Musk has around 57 million followers on Twitter. If only some of them get involved in the crypto currency in Musk's Bitcoin tweets, this can move the price significantly.