Russian President Vladimir Putin has spoken of his regret at the fall of the Soviet Union in 1991, revealing that he had to work as a taxi driver to supplement his income.

Economic troubles triggered by the collapse forced many Russians to seek new ways to earn money.

Mr Putin described the break-up as the collapse of historical Russia.

The remarks could fuel speculation about his intentions towards Ukraine, a former Soviet republic.

Russia has amassed more than 90,000 troops on its border with Ukraine and there are fears it is planning to invade.

Russia denies this, accusing Ukraine of provocation and seeking guarantees against eastward Nato expansion.

Mr Putin's remarks come from a documentary film called Russia, Latest History, aired on Sunday.

"It was a disintegration of historical Russia under the name of the Soviet Union," he said, adding that in the West it was believed that the further disintegration of Russia was only a matter of time.

It is well known that Mr Putin views the collapse as a tragedy but his remarks about his personal difficulties at the time are new.

"Sometimes I had to earn extra money," he said. "I mean, earn extra money by car, as a private driver. It's unpleasant to talk about to be honest, but unfortunately that was the case."

At the time, taxis were a rarity in Russia, and many private individuals would give rides to strangers to help make ends meet. Some would even use work vehicles such as ambulances as taxis.

Mr Putin is known to be a former agent of the Soviet security service, the KGB.

However, in the early 1990s he worked in the office of St Petersburg Mayor Anatoly Sobchak. He maintains that he resigned from the KGB after the August 1991 coup against Soviet President Mikhail Gorbachev which led to the break-up of the USSR. (BBC: Vladimir Putin: I moonlighted as a taxi driver in the 1990s)

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