Minicab service company Uber has been charging customers almost three times as much for its standard rate during London's Tube strike, which started at 5.30pm on 8 July.

The scandal-ridden taxi firm's popular app gives a signal that, due to a high amount of customers, the basic rate is 2.9 times as high as normal because Tube workers are on strike to protest the 24-hour Tube terms.

"Demand is off the charts! Fares have increased to get more Ubers on the road," the message sent to app users read.

The Tube strike, thought to be the largest since 2002, has caused chaos across the capital as all underground stations are closed. Uber's decision to impose a rate increase has been criticised by commuters.

Other taxi companies have also seen a major rise in sales volumes. Taxi firm Hailo reported the number of customers who signed up to the company's service in the week of the strike was 174% higher than the average week.

Hailo's chief executive Andrew Pinnington told IBTimes: "It's been all hands on deck since five o'clock this morning [9 July] really."

"I think we will end up, in total, getting nearly ten times as many pre-books as normal, Pinnington said. "That just shows how much demand we are seeing at the moment. I have no doubt there are a lot of happy taxi drivers out there today."

Hailo did well, the CEO said, although it took taxi drivers a bit longer on average to get to the customers.

"Our attitude is that, the black cab service is about security, safety and reliability. We are not taking this as a chance to take advantage of consumers, we are just doing our best to provide the best service possible," he added.

Many cab services advise commuters to pre-book taxis in order to avoid queues. Uber could not provide a comment in time.