LONDON/TOKYO (Reuters) - Bitcoin fell as much as 20 percent on Wednesday, piercing below $10,000, while other cryptocurrencies took similar spills due to investor fears that regulators could clamp down on them in an effort to curb speculation.

The world's biggest and best-known cryptocurrency at one point lost 30 percent of its value since Tuesday. Bitcoin, despite some stabilization in late U.S. trading, was half its record peak of almost $20,000 set on the Luxembourg-based Bitstamp exchange BTC=BTSP a month ago.

Ethereum and Ripple .MVXRP, the No. 2 and No. 3 virtual currencies, tumbled after reports South Korea and China could ban cryptocurrency trading, sparking worries of a wider regulatory crackdown.

“There is a lot of panic in the market. People are selling to try and get the hell out of there,” said Charles Hayter, founder of Cryptocompare, which owns cryptocurrencies.

“You have more regulatory uncertainty ... and because of these falls, you have these other fallouts,” he said, referring to the collapse of some cryptocurrencies in the recent slump in prices.

Analysts at Citi said on Wednesday bitcoin could halve again in value amid the current rout, adding that a possible fall to a range between $5,605 and $5,673 “looks very likely to be very speedy”.

With South Korea, Japan and China all making noises about a regulatory swoop, and officials in France and the United States vowing to investigate cryptocurrencies, there are concerns that global coordination on how to regulate them will accelerate.

Officials are expected to debate the rise of bitcoin at the upcoming G20 summit in Argentina in March.

“Cryptocurrencies could be capped in the current quarter ahead of the G20 meeting in March, where policymakers could discuss tighter regulations,” said Shuhei Fujise, chief analyst at Alt Design.

Broken representation of the Bitcoin virtual currency, placed on a monitor that displays stock graph and binary codes, are seen in this illustration picture, December 21, 2017. REUTERS/Dado Ruvic/Illustration/Files

REVERSAL OF FORTUNES

The current rout in bitcoin and other digital currencies was a far cry from their dramatic run-up in 2017 when mainstream investors jumped on the bandwagon and as an explosion in so-called initial coin offerings (ICOs) - digital, token-based fundraising rounds - drove demand.

“Bitcoin is deciding whether this is the moment to crash and burn,” said Steven Englander, head of strategy at New York-based Rafiki Capital.

Bitcoin has plummeted before.

There have been nine instances including the current selloff going back to 2011 where bitcoin's price was halved on the Bitstamp exchange BTC=BTSP. The last time was from November 2014 to January 2015.

On Wednesday, bitcoin fell as low as $9,222 on Bitstamp, its lowest price since Dec. 1, as CBOE and CME bitcoin futures XBTF8BTCF8 tumbled to contract lows.

The latest market losses stemmed from reports that South Korea’s finance minister said banning trading in cryptocurrencies is still an option and that Seoul plans a set of measures to clamp down on the “irrational” cryptocurrency investment craze.

Separately, a senior Chinese central banker said authorities should ban centralised trading of virtual currencies as well as individuals and businesses that provide related services.

“My conjecture is that cryptocurrency holders are trying to decide whether to abandon bitcoin because its limitations mean it will be superseded by better products or bet that it can thrive despite them,” Englander said.

BUBBLE BURST?

While many observers say the recent falls show that the bubble has burst, those backing the nascent markets say that regulation is welcomed and wild price swings to be expected.

“The volatility of bitcoin - and other cryptocurrencies - is an expected, and important, part of the journey to becoming a mature asset class. We expect the volatility to continue throughout 2018 but fundamentally believe that bitcoin is still in a bull market,” said Christopher Keshian, co-founder of $APEX Token Fund.

Ethereum, the second-largest cryptocurrency by market value, was down 15 percent since Tuesday, according to website CoinMarketCap.

Ripple, the third-biggest, has lost 18 percent of its value over the past 24 hours and was quoted at $1.03, down from a high of $3.81 on Jan. 4.

“The run-up in bitcoin created a mystique of one-way trading which is being shaken, but the pricing requires faith that there will always be demand,” Englander wrote in a research note. “This is far from guaranteed given the existence of alternatives with better characteristics.”