A fund owned by Russia's largest lender Sberbank has deepened its cooperation with controversial ride-sharing app Uber by committing an undisclosed amount in its latest investment round.

Sberbank's SBT Venture Fund I, managed by MoneyTime Ventures, has taken part in Uber's Series G investment round. according to an emailed statement from Sberbank. The Russia lender, which controls about 46% of the nation's deposits, joins Russian billionaires Mikhail Fridman and Alisher Usmanov in betting on the popular mobile app. 

"We are keen on investing in Uber," said Victor Orlovsky, general partner of MoneyTime Ventures, said. "I'm certain this is a promising investment considering both the potential of our cooperation and the investment potential for our fund."

Based on its other tech investments, Sberbank's initial punt on California-based Uber is likely to be about $10-$25mn, a tiny amount compared with sums pumped in by other investors. Fridman, for example, invested about $200mn from his LetterOne holding in February, while Usmanov is reported to have ploughed several tens of millions in Uber a year ago.

Apart from investing, Sberbank is also considering the potential for further collaboration with Uber, which has spread like wildfire to 12 Russian cities since arriving in the country in December 2013.

Sberbank is interested in improving the quality of service it provides its customers when they use popular digital services and is actively developing its cooperation with Uber and other companies of the new digital economy.

Uber's latest investment round, which Sberbank participated in, was closed in the spring of 2016. That brough the total volume of investments in Uber to $11bn. The biggest single investment was a hefty $3.5bn punt made by Saudi Arabia's Public Investment Fund, valuing the company at a staggering $62.5bn. 

Sberbank set up its venture fund in 2013 and it has assets already of about $100mn. its focus is on early-stage growth companies alreadyg generating revenue and in need of "capital, brains and the right network to reach scale," according to its website. 

The fund has invested sums of $8mn to $27mn in companies such as online bank Moven to eToro, a multi-asset broker and social trading nework, according to Crunchbase, the database of startups. 

Sberbank head Herman Gref is known for his love of technology and latching on to the latest fads. The bank first declared its interest in Uber in September last year.

Uber, which in late April slashed the price of a fare to Moscow city's three main airports beginning RUB700 ($11), has drawn the ire of Moscow's legitimate and unlicensed cab drivers alike since arriving in Russia – much the same has it has done wherever in the world it appears.

Cabbies came out on strike last year in Moscow and St Petersburg against Uber and other ride-sharing apps like Yandex.Taxi and Get.Taxi for their price-cutting. The union of taxis wrote to the Kremlin, demanding Uber drivers be required to register with the state and receive official status for transporting passengers or face criminal liability.

Since launching in Moscow and St Petersburg, Uber has spread to  Chelyabinsk, Ekaterinburg, Kazan, Krasnodar, Krasnoyarsk, Nizhny Novgorod, Novosibirsk, Rostov-on-Don, Ufa and Sochi, pursuing its goal of operating in all Russian cities with more than one million residents by the end of 2016.

Uber has been accused of using its massive financial weight to sink  competitors. When it arrives in a new market, it attracts drivers to its platform with bonus paychecks and minimal commissions. Since beginning in 2010, Uber has entered a new city every five days and reportedly run up losses of hundreds of millions of dollars.

Its billionaire tech backers foot the bill without batting an eye-lid, betting on future profits once the company has conquered the world.