Belarusian-born prominent journalist Pavel Sheremet has been killed in a car bombing

A prominent journalist and critic of Vladimir Putin has been killed in a car explosion in central Kiev.

Ukrainian authorities are treating 44-year-old Pavel Sheremet's death as murder.

Two eyewitnesses told Reuters they heard a loud blast and saw an explosion from underneath the car, which was found charred in the middle of the cobbled street.

The car exploded soon after Sheremet left his home in the Ukrainian capital and the vehicle was burned out completely.

Police believe an explosive device was placed under the driver's seat.

Sheremet worked for the country's top online news website Ukrainska Pravda. The publication said he was about to drive to work to anchor a talk show on a local radio station when he was killed.

The car was owned by the publication's editor-in-chief - Sheremet's partner - Olena Prytula.

During his career, the Belarusian-born journalist irked officials in Belarus and Russia before he moved to Ukraine in 2014 after making clear his opposition to Putin's policies on Ukraine.

Authorities are checking three theories regarding his death - his professional activity as a journalist, personal enmity, and a 'Russian trace', said Interior Ministry official Zorian Shkiryak.

The explosive device - of up to 600 grams in TNT or equivalent - set off in the car is believed to have been detonated by remote control.

'I named three main versions that are not ruled out - his professional activity [and] hostile relations, (and) of course we should be well aware that when a hybrid war is waged against us, considering how professionally this bloody murder was committed, we cannot exclude a Russian trace,' Shkiryak said.

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Firefighters examine the wreckage of the car Pavel Sheremet was killed in on Wednesday morning

Sheremet worked for the country's top online news website Ukrainska Pravda. The publication said he was about to drive to work to anchor a talk show on a local radio station when he was killed

The journalist was close to Russian opposition leader Boris Nemtsov who was gunned down outside the Kremlin last year.

He described the slain politician as 'like my elder brother', and had blamed Moscow's secret services for involvement in the killing.

It is believed that Nemtsov had met Sheremet in Kiev only days before he was shot in Moscow.

In a testimony to investigators, Nemtsov's glamorous Ukrainian model girlfriend Anna Duritskaya was asked who Nemtsov's friends were in Ukraine.

'Journalist Pavel Sheremet, I don't know anybody else,' she told them in leaked testimony.

There was speculation today that Sheremet's death could be linked to that of Nemtsov, in which Moscow investigators see a trace to Chechnya.

Sheremet had also accused Putin of wanted a huge carve-up of Ukraine, cutting its access to the Black Sea, which 'will allow Russia to cut into the body of the Eastern Europe'.

The car was owned by Sheremet's partner Olena Prytula. She is also the editor-in-chief of news website Ukrainska Pravda

The car exploded soon after Sheremet left his home in the Ukrainian capital and the vehicle was burned out completely

The Minsk-born journalist had also sharply criticised the Belarus dictator Alexander Lukashenko.

In 1997, Belarus convicted Sheremet of illegally crossing its border and sentenced him to three years in prison for his investigation on the porous border between Belarus and Lithuania.

He served three months in prison before he was released.

Sheremet faced threats and harassment in Belarus and was badly beaten in 2004 while covering an election. Several years later he moved to Russia to work in television.

In a media landscape sanitized by the authoritarian Belarusian government, Sheremet — while living abroad — founded Belaruspartisan.org which went on to become one of the country's leading independent news websites.

He moved to Ukraine in 2014 after what he said was pressure from his Russian television bosses over the reporting of ongoing opposition protests in Kiev.

A shaken Ukrainian president Petro Poroshenko said: 'A terrible tragedy in Kiev.

In this photo the car can be seen burning after the explosion in Ukraine's capital

'Shock - I have no other words for it. I knew Pavel [Sheremet] personally.

'My condolences to all his near and dear. I have ordered law-enforcement agencies to investigate this crime urgently.

'Those guilty must be punished.'

The head of Ukraine's national police force Khatia Dekanoidze said: 'I will personally take charge of the case.'

Prime Minister Volodymyr Groysman posted a message on Facebook saying: 'The day has begun with terrible news. The prominent Ukrainian journalist Pavel Sheremet was killed this morning.'

In Ukraine, Sheremet worked for Ukrainskaya Pravda newspaper. He had lived in Kiev for five years.

Pavel Sheremet (right) with Boris Nemtsov (left). Russian opposition leader Nemtsov was gunned down outside the Kremlin last year. It is believed that Nemtsov had met Sheremet in Kiev only days before he was shot in Moscow.

In a testimony to investigators, Nemtsov's glamorous Ukrainian model girlfriend Anna Duritskaya was asked who Nemtsov's friends were in Ukraine. 'Journalist Pavel Sheremet, I don't know anybody else,' she told them in leaked testimony.

His partner was Alyona Pritula, the founder and chief editor of the title.

The car was hers, but she was not in the vehicle at the time.

A spokesman for the Ukrainian general prosecutor said: 'Investigators preliminarily qualify this event as murder. A pre-trial investigation has been launched.'

The car exploded on the corner of Bogdana Khmelnitskogo and Ivana Franko streets, opposite McDonald's.

MP Anton Gerashchenko, an aide to the Interior Minister, said: 'This is a cynical and well-planned murder.

Pavel Sheremet was a respected journalist. He is pictured here with Elton John (right).

'The investigation will be looking into all possible versions of the murder of Pavel Sheremet, first of all those linked to his journalism activities, not excluding a Russian trace.

'My apologies to Pavel Sheremet's family and friends.'

Newspaper Komsomolskaya Pravda in Ukraine today warned that 'the murder of Russian oppositionist Boris Nemtsov and journalist Pavel Sheremet may be links of one chain.'

The cited Ukrainian politician Ostap Semerak who said: 'It was Boris who got me acquainted with Pavel.

'Both were killed. Rest in peace.

'The last time I saw Boris was with Pavel.

'We met in Kiev and had a lengthy discussion on Russia's aggression against Ukraine. They condemned the Kremlin's actions.

'They were killed in a cowardly way by a shot in the back - and explosives in the car.'

Ukrainian police officers and security services experts examine the charred car