One of Uber Technologies' biggest rivals in the London taxi market is close to securing more than $100m (£78m) in new funding from investors.
Sky News has learnt that Bolt, which was previously called Taxify, is working with Goldman Sachs on a fresh round of funding just four months after raising about £50m from new and existing backers.
Sources said the latest capital injection was expected to be finalised in the coming weeks, and would cement Bolt's "unicorn" valuation of $1bn.
The disclosure that the ride-hailing app is close to raising further funding comes a day after regulators confirmed the withdrawal of Uber's licence.
Sky News revealed at the weekend that Transport for London (TfL) was actively considering a ban for Uber amid doubts about its ability to identify its own drivers.
The watchdog said on Monday that a change to Uber's systems had enabled unauthorised drivers to upload their photographs to other Uber driver accounts - a failing that occurred in at least 14,000 trips.
Uber, the world's biggest ride-hailing app, depends on London for the profit it generates for the wider, loss-making business.
It said it would appeal against TfL's ruling.
In response, Bolt said it had "spent a year working with TfL on our successful London licence application and we continue to pay the utmost attention to the credentials of drivers we permit to use our platform.
"Our vision for the future of urban mobility in London, and cities around the world, demands our commitment to delivering the value, quality, safety and care for the environment our customers expect."
Since launching in London in June, Bolt has signed up more than 300,000 customers, and registered 30,000 drivers - making it a significant player in a market that now includes Kapten, Ola and traditional rivals such as Addison Lee.
The Estonia-based company has raised more than $200m (£155m) to date, with investors including the giant German car manufacturer Daimler, Chinese ridesharing service Didi Chuxing, and Taavet Hinrikus, the co-founder of TransferWise.
Bolt operates in more than 100 cities in 35 countries across Europe and Africa.
Recent launches have included Stockholm and St Petersburg.
Bolt and Goldman declined to comment on Tuesday.