Uber has hit out at regulations being introduced in Dubai that impose extra fees on private taxi fares.

Dubai transport regulator the Roads and Transport Authority (RTA) is enforcing a new set of regulations that include an extra AED5 ($1.36) per fare surcharge payable by operators.

The RTA has yet to make the regulations public, and did provide further information.

However, Uber and its rival Careem are understood to have been made aware of the changes, which, according to the Financial Times, came into force at the weekend.

Private car hire operators in the emirate are already required to pay the government a levy 30 percent higher than taxi services – squeezing their margins, they say.

Uber said this week that any additional increase is likely to impact the service it provides.

In a statement to Arabian Business, a spokesperson for Uber said: “New regulations have not yet been made public.

“However, we have been operating at 30 percent above taxis, as per the current requirements, and any additional increase in fees makes it more difficult for us to provide a service that fits our vision for affordable, reliable transportation.”

A spokesperson for rival car hire app Careem said the company was compiling a statement on the additional fare surcharges, but it had yet to respond at the time of publication.

Meanwhile on Tuesday, the RTA announced it had entered into a partnership with rival taxi hire app Careem, under which Careem customers will be able to book a taxi through RTA channels.

It is understood to be part of a string of digital partnerships planned between the Dubai government and private sector firms to help transform Dubai into one of the world’s ‘smart cities’.

Under the deal between Careem and Dubai's Roads and Transport Authority (RTA), Careem's customers will be able to book all of the 9,841 taxis and 4,700 limousines operating in the emirate through the company's app.

Currently, Careem users in Dubai, a city of about 2.5 million people, can only choose from a few thousand limousines which it offers through its app.

"Any e-hailing service that wants to continue working in Dubai must sign an agreement with us. Why? To have control of tariff and to have control of safety," RTA director-general Mattar al-Tayer told Reuters.

He said other ride-hailing services would have to sign similar agreements with the regulator by next March to continue operating.

The requirement is a further challenge to Uber in the UAE. Its services in the emirate of Abu Dhabi, bordering Dubai, have been suspended since August in an apparent dispute with authorities there. Careem also halted its Abu Dhabi services in late August but resumed them a few days later.

RTA deal with Careem

Dubai's RTA and Careem did not reveal the pricing details of their deal, but said it would involve no additional costs for customers. Launched in Dubai in 2012, Careem has emerged as Uber's fiercest rival in the Middle East and North Africa, and claims over 4 million registered users.

"This does give us access to a much bigger fleet of cars, so we believe it gives us a significant advantage over competitors," Careem's co-founder and managing director Mudassir Sheikha said of his deal with the RTA.

Uber said it had been in discussions with the RTA for the last two years on how it could make Uber more available to riders in Dubai.

A source familiar with the issue told Reuters that Uber was also concerned by the RTA's plan to set up a platform to integrate data from ride-hailing services in Dubai, which could create security and privacy risks.

Launched in Dubai by Sheikha and fellow McKinsey & Co alumnus Magnus Olsson, Careem raised $60 million last November through an investment led by private equity company Abraaj Group.

The company counts Saudi Arabia's Al Tayyar Travel Group as its largest investor and has also received backing from STC Ventures, an independently managed venture capital fund that has the Saudi Telecom Company as anchor investor.

Uber, in which a Saudi Arabian sovereign wealth fund bought a $3.5 billion stake in June, said last year that it planned to invest $250 million to expand in the Middle East and North Africa.