But it also insisted that the colourful "Yo Mobiles" were never designed as a publicity stunt to win the politically ambitious metals and banking magnate votes in last spring's presidential elections.

"Many detractors will now say that this was just a Mikhail Prokhorov PR campaign," project general director Andrei Biryukov told Russian news agencies after tendering his resignation because of the delay.

"But this is not the case and he continues to fund the joint venture."

Biryukov blamed the problem on a US supplier he did not name that was responsible for providing parts for the vehicle's four-wheel-drive models.

The eye-catching little vehicles were meant to give a fresh new look to Russian streets clogged with the last remnants of exhaust-fuming Soviet-era makes and huge SUVs and luxury sedans from the United States and Germany.

President Vladimir Putin drove one of the cars to a government meeting while serving as prime minister in April 2011 and joked that it did not look particularly sturdy.

"The Yo-Mobile will not fall apart along the way, will it?" Putin asked with a grin at the time.

It has in fact been skewered by auto critics as having a dangerously high centre of gravity that could make the car roll over.

Others question the design for its outdated power management and storage method with some have even calling the future cars dangerous.

Several motor specialists said the announcement effectively burst Russia's hybrid dreams for the near future.

"The Yo Mobile is no more," the AvtoItogi.ru specialist website wrote.

"The future of Yo autos is in grave doubt," observers at CarTimes.ru said.

The project had folded neatly into Prokhorov's efforts to build a modern image of an oligarch who occasionally supports liberal causes and connects with the youth through his ownership of the NBA's Brooklyn Nets basketball team.

The 47-year-old -- last estimated to be worth more than $12 billion by Forbes magazine -- placed a strong third in the March presidential ballot with a surprising eight percent of the vote.

Most of those came from upper and middle class voters in Moscow and Saint Petersburg who would have been the first to jump in his cars.

Prokhorov's campaign came during a wave of street protests against Putin's impending return to the Kremlin and Prokhorov styled himself as a compromise figure who would introduce more liberal economic ideas.

He has largely shunned politics since and is still in the process of forming his own political party while refusing to criticise Putin directly.

Prokhorov's Oneximbank bank and a small truck manufacturer called Yarovit Motors had already invested 80 million euros ($100 million) in the vehicle's Saint Petersburg plant through June.

It also promised to roll out its first vehicles for the highly competitive price of just $15,000 -- a fraction of its main Asian rivals.

Biryukov said the unspecified US delay will now force the company to temporarily shelve plans to build its "Yo Crossover" and move on straight to its "G class" off-road vehicles.

"We intend to introduce the new G class model in the first half of 2013," Biryukov said.