Uber just lost its license to operate in London. Again.

Uber has lost its license to operate in London. Yes, again.

Announced Monday, Transport for London (TfL), which regulates taxis and private hire services in the city, has denied Uber's latest license application, citing "several breaches that placed passengers and their safety at risk."

The company lost its licence in 2017 due to safety concerns, but landed a 15-month extension in June 2018 after which it was able to continue operating.

"As the regulator of private hire services in London we are required to make a decision today on whether Uber is fit and proper to hold a licence," said Helen Chapman, TfL's director of licensing, regulation and charging, in a press statement.

"Safety is our absolute top priority. While we recognise Uber has made improvements, it is unacceptable that Uber has allowed passengers to get into minicabs with drivers who are potentially unlicensed and uninsured."

TfL said the key passenger safety concerns were related to unlicensed and uninsured drivers finding loopholes in Uber's system. One in particular was a change which allowed unauthorised drivers to upload their photos to other Uber driver accounts. This meant these drivers could pick passengers up pretending to be a booked driver, and according to TfL, this happened in a staggering 14,000 trips.

Another issue, TfL said, allowed dismissed or suspended drivers to create an Uber account and carry passengers.

London Mayor Sadiq Khan said he supported TfL's decision, issuing a statement on Twitter.

"Only in the last few months it has been established that 14,000 Uber journeys have involved fraudulent drivers uploading their photos to other driver accounts — with passengers' safety potentially put at risk getting into cars with unlicensed and suspended drivers," he wrote.

"I know this decision may be unpopular with Uber users but their safety is the paramount concern."

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Londoners won't be without Uber just yet. Uber can appeal the decision within 21 days, and operate as normal within that timeframe. According to Chapman, Uber "will have the opportunity to publicly demonstrate to a magistrate whether it has put in place sufficient measures to ensure potential safety risks to passengers are eliminated."

Uber has, of course, vowed to launch an appeal. In a statement emailed to customers on Monday, Uber called the decision simply "wrong," and noted TfL had even granted the company a two-month license in Sept. 2019 to bridge the gap between the end of their 15-month extension and Monday's decision.

"We think this decision is wrong and we will appeal. You and the 3.5 million riders who rely on Uber in London can continue to use the app as normal," the statement read.

"Over the last two years we have fundamentally changed our business, and TfL found us to be a fit and proper operator just two months ago."

Uber CEO Dara Khosrowshahi criticised the decision and reiterated the company's statement on Twitter.

"We understand we’re held to a high bar, as we should be. But this TfL decision is just wrong," he wrote.

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According to the BBC, there are currently about 45,000 Uber drivers working in London, all of whom could be without a job if the company's appeal doesn't work.

Mashable has reached out to Uber for further comment.

UPDATE: Nov. 25, 2019, 11:43 a.m. GMT Added Uber CEO Dara Khosrowshahi's statement.