Rescuers at one of Russia's largest diamond mines were searching late into the night on Friday for nine miners still unaccounted for after water leaked into an underground shaft with more than 100 workers inside.

Alrosa, Russia's largest diamond producer, said in a statement that "nine people are being searched for" after water broke through into the Mir mine in the Sakha region some 4,160 kilometres (2,600 miles) east of Moscow at around 0730 GMT.

The emergency situations ministry for the region said rescuers were "carrying out a search of the mine's workings in order to find and save people".

The water leaked into one of the mine's pumping stations out of a flooded disused crater that contained some 300,000 cubic metres of water, or the equivalent of 120 Olympic-size swimming pools, the emergency situations ministry said.

The accident is believed to have been caused by an "uncontrolled increase in the flow of water" out of the mine's abandoned crater into the underground shaft, Alrosa said.

It said this was caused by sudden geological processes and the washing away of rocks in the crater but insisted that all of the mine's "equipment has been regularly tested."

The Sakha region's branch of the Investigative Committee, which probes serious crimes, said in a statement that it was carrying out a check into possible safety violations at the mine.

Russian television said the rescue operation at the mine named Mir, or peace in Russian, was hindered by a power cut that stopped the lift system from working.

Channels showed footage posted on social media of water flooding into a control room and coming from the ceiling of underground passageways.

Alrosa said that 133 people have been evacuated from the mine. Two were taken to hospital with minor injuries, the region's health ministry said.

- Vast crater -

Russian President Vladimir Putin, who visited Siberia this morning, has been briefed about the accident, his spokesman Dmitry Peskov told TASS state news agency.

Alrosa's president Sergei Ivanov flew to the scene as did the leader of the Sakha region, Yegor Borisov, who brought additional backup including surgeons and doctors specialising in emergency medicine.

Emergency Situations Minister Vladimir Puchkov also travelled to the scene.

"Search and rescue operations will continue until the circumstances (of the accident) become clear," he was quoted as saying by TASS.

Alrosa's president, Sergei Ivanov, is the 36-year-old son of Putin's former chief of staff, also called Sergei Ivanov. He has headed Alrosa since March this year.

Alrosa, based in the Sakha region, made a net profit of 22.7 billion rubles ($376.37 million) in the first quarter of 2017.

The Mir mine was launched in 2009 and produces a million tonnes of diamond ore per year. Last year the diamonds it produced totalled 3.19 million carats, according to the company's website.

Up to 2001, Alrosa used opencast mining at the Mir site, which has been used for diamond production since 1955. The opencast mine is a vast round crater with a diameter of over a kilometre that is one of the largest manmade holes on Earth.

The last major mining accident in Russia saw 36 people killed by methane explosions that ripped through Severnaya coal mine north of the Arctic Circle in February 2016.

In 2010, 91 people died after a methane explosion at the Raspadskaya coal mine in the Siberian region of Kemerovo.

Source: AFP