One of Russia's richest women has died alongside her father after their private plane crashed in Germany.

Natalia Fileva, 55, and Valery Karachev were killed on Sunday when their plane fell from the sky as they were flying from France to Egelsbach in Germany.

Also killed was their pilot, named in Russian media as Andrey Dikun. Sources told Russian media that the pair were travelling for medical treatment, but did not give more details.

Two more people are believed to have died in a collision with a police vehicle which was responding to the scene.

Airline tycoon Natalia Fileva (pictured), the co-owner of Russian carrier S7, was on board a six-seater plane which crashed and exploded near Frankfurt on Sunday

Also killed in the fireball crash were Fileva's father Valery Karachev and their pilot Andrey Dikun, sources told Russian media (pictured, the plane wreckage)

Police said the six-seater Epic-LT private plane took off in France and was on its way to the central German town of Egelsbach.

It crashed and burned in an asparagus field near Erzhausen, six miles south of Frankfurt, at around 3.30pm.

The tragedy was compounded when a police car carrying two officers to the crash site collided with two further vehicles on the way.

The second vehicle, an Opel car, was carrying two young people who died in the crash while the police officers were seriously injured.

The victims of the car accident were a 24-year-old man and a 22-year-old woman, police said.

Fileva became known as the 'Iron Lady' of the air industry after amassing a personal fortune of £460million after she founded airline S7 with her husband.

The company, based in Siberia, is Russia's second-largest behind state flag-carrier Aeroflot.

She eschewed the flamboyance of some Russian multi-millionaires after an extraordinary rise from Young Communist activist in Soviet times to Moscow's fourth richest woman.

Her husband and business partner ex-pilot Vladislav Filev, 55, has been called the Russian Elon Musk but she strove to keep her family out of the limelight as she conquered the male-dominated aviation industry in her country.

The couple had four children, one adopted, including two adult girls, say reports.

Fileva was on her way from Cannes to Egelsbach for medical treatment when her plane came down in an asparagus field and burst into flames around 3.30pm on Sunday

An official with Deutsche Flugsicherung (DFS), the company in charge of air traffic control for Germany, told TASS that the pilot presumably lost control of the aircraft while performing a turn.

'I cannot say for sure what caused the tragedy, but I may presume that the pilot possibly lost control of the aircraft for some reason while performing a turn,' he said.

The turboprop plane was destroyed as it hit the ground in a fireball.

The official said the pilot steered the plane under the Visual Flight Rules (VFR), not instructions from DFS radars, which is a standard procedure when weather conditions are generally good and visibility is sufficient.

S7 issued a statement saying: 'On March 31, 2019, S7 Airlines shareholder Natalia Valeryevna Fileva died at the age of 55 when her private Epic-LT plane was preparing to land at Egelsbach Airport (Frankfurt-on-Main).

'The circumstances of this tragedy are not known.'

The company added that the air disaster would be investigated by an international commission along with Russian air safety authorities.

The German Federal Bureau of Aircraft Accident Investigation (BFU) has launched an investigation into the accident.

Fileva and her husband gained control of the ailing Siberia Airlines company in the aftermath of the Soviet collapse and built it in to an international carrier which for a decade had been part of the OneWorld Alliance alongside American Airlines, British Airways and Japan Airlines.

In December she had a public blast at official corruption in Russia implying bureaucrats were bribe-takers.

'They don't do business, they are not real people,' she said scornfully.

'You are talking about fighting corruption.

Emergency services work among burnt out debris of a small aircraft on a field near the small airport of Egelsbach following the crash in Germany on Sunday

The remains of a police car which crashed into another vehicle near Frankfurt, on the way to the scene of a plane crash in which a Russian millionaire died

'And I want to ask where they get money for their suits and shoes?

'Everyone of them has a suit which costs at least $1000 (USD).'

Fileva had been an activist in the Komsomol - or Young Communists - in the Soviet era.

She trained as a radio mechanic in her native Novosibirsk before getting a second degree in industrial management.

The couple were seen as a highly successful husband and wife business team.

Leading business journalist Renata Yambayeva, said Fileva was 'a true aviator and a real woman'.

'I knew her from the first days when the Filevs purchased Siberia Airlines (later S7).

'She was always the heart of this business.

'She was its wings.

'Back then in a very tough and male-dominated Russian aviation these two aliens not just survived but forced everyone respect them….to respect them together.'

Fileva 'could smile, terrify, be soft and be made of iron'.

She was planning to make S7 a leading player in sea-based rocket launches to put satellites into space.

The head of the Russian space agency Dmitry Rogozin said: 'Her death is a personal tragedy for us all.'

Irkutsk airport chief Andrey Andreev said: 'The Filev couple were nicknamed Mama and Papa among S7 Group staff.

'Many felt they were orphaned today.

'It is incredibly painful that Natalia Fileva, a formidable woman, a bright personality and a professional to every cell of her bones, is no longer with us.

'She combined humanity and entrepreneurship, the romanticism of aviation and understanding of world aviation trends.'

She led the way in improving the Russian air fleet, he said, 'setting an example to many state officials in aviation'.

'Thanks to her energy and pushing skills the Russian aviation code was modernised and got closer to world standards'.

Her daughter Tatiana is reported to work for the airline.

Maria is a student at the Moscow Aviation Institute.