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LONDON (Reuters) - Bitcoin regained its footing on Monday, having suffered its heftiest falls since early 2015 between Thursday and Saturday as investors sold the digital currency on worries about its future.

Having soared to an all-time high of $1,350 BTC=BTSP on the Bitstamp exchange on March 10, on speculation that regulators could approve the first U.S. bitcoin exchange traded fund the following day, the digital currency then slipped back.

Its falls began accelerating on Thursday and it hit a five-week low of $944.36 on Saturday. But bitcoin recovered a little on Sunday and built on those gains on Monday, climbing around 2.5 percent to roughly $1,050 by 1815 GMT.

Bitcoin experts said its steep losses were driven by a longstanding, and intensifying, row over whether - and how - to increase the capacity of the “blocks” that bitcoin transactions are processed in, so as to make sure there are no delays in transactions being finalised.

“The bitcoin scaling debate is a risk for the network and highlights core issues in terms of governance and this is where more nimble crypto competitors see advantages in fleshing out their capabilities sooner,” said Charles Hayter, CEO of digital currency analysis website Crytocompare, in London.

At the same time that bitcoin was plunging, a newer, rival “cryptocurrency” was soaring: ether. The digital currency behind Ethereum - a project that some experts say holds more potential than bitcoin - has almost tripled in value this month, jumping to record highs of around $45.

Some experts said traders were selling bitcoin and buying ether, which was exacerbating the falls in the original cryptocurrency.

“Traders in the space are looking for better returns in the more risky and nascent cryptos such as Dash, Monero and Ethereum (and are) looking to replicate the extraordinary returns that bitcoin saw in its early days,” added Hayter.

U.S. regulators dashed Cameron and Tyler Winklevoss’s bitcoin ambitions earlier in the month by rejecting their application to list an exchange-traded fund linked to the digital currency.