The cryptocurrency arm of Fidelity Investments, one of the world's largest investment managers, has launched its first foray into Europe, opening a new front in efforts to drag digital money into mainstream investing.

Fidelity Digital Assets will act as a custodian for bitcoin held by London-based cryptocurrency investment firm Nickel Digital Asset Management, the two companies said on Tuesday.

The lack of back-office services like custody offered by major financial firms has been one reason that large investors across the world have held back from involvement in the highly volatile but potentially lucrative emerging asset.

Yet it remains to be whether the provision of such services alone by firms like Boston-based Fidelity, which has $7.8 trillion under management, will pave the way for an influx of mainstream money into cryptocurrencies.

Big pension funds and asset managers remain highly sceptical of digital currencies because of their patchy regulation and reputation for hacks, heists and other crime, despite the large potential gains on offer.

Bitcoin almost doubled in value last year, buoyed by expectations of growing mainstream use. Yet bitcoin markets are dysfunctional and plagued by double-digit price swings, opaque price discovery and patchy liquidity.