British fintech company Revolut swung to a pretax profit of 438 million pounds ($553.81 million) in 2023 on strong user growth and interest-related income, against a pretax loss of 25.4 million pounds a year earlier.

The company's revenue almost doubled to a forecast-beating 1.8 billion pounds, its annual report said on Tuesday.

The growth comes at an opportune time, with the company seeking a more than $40 billion valuation in a $500 million share sale. That would cement its place as Europe's most valuable startup.

Revolut has applied for a UK banking licence but three years on is still awaiting approval.

In an interview with CNBC, Revolut CEO Nikolay Storonsky said he was optimistic of the company's chances of being granted a UK licence.

Revolut is "continuing to work closely" with UK regulators on its UK bank licence application, the annual report said.

The company has faced problems with its financial reporting previously, drawing scrutiny from regulators, and delayed publication of both its 2021 and 2022 accounts.

When the 2021 accounts were finally published in March 2023, auditor BDO said it was unable to independently verify three quarters of the 636 million pounds of revenue. Its 2023 numbers were not due until September.

Britain's fintech industry has faced a funding crunch in recent years as investors have become more sceptical of sky-high pandemic-era valuations and put pressure on companies to become profitable.

Founded in 2015, Revolut is one of a handful of fintech companies to have emerged in Britain over the past decade, offering financial services without having physical branches. It has 45 million customers globally, with customer numbers increasing by nearly 45% last year.

Revolut's customer loan book grew to more than 500 million pounds in 2023, up from 204 million the previous year, the report said.

Income from higher interest rates, which has boosted banks across the board, accounted for 500 million of the 1.8 billion pounds of revenue, Revolut said.

($1 = 0.7909 pounds)

(Reporting by Elizabeth Howcroft in London and Utkarsh Shetti in Bengaluru; Editing by Alan Barona and David Goodman)