The Turkish assassin of the Kremlin's envoy in Ankara had been involved in a sexual relationship with a Russian woman who could have been planted by Western secret services, according to a sensational new report.

Ambassador Andrey Karlov was gunned down in Ankara by 22-year-old police recruit Mevlut Mert Altintas who shouted 'Allahu Akbar' and 'Don't forget Aleppo' as he murdered the respected diplomat before he was shot dead.

And now there are claims in Turkish media that Altintas had a lover from Russia or another associate, who may have brainwashed him into committing the murderous act last week.

A new report has claimed that Mevlut Mert Altintas who gunned down Russian ambassador Andrey Karlov in Ankara, may have been involved in a sexual relationship with a Russian woman

A Turkish report which has been seized on by Russian media said: 'It is very important to understand who the woman is: from intelligence, FETO or mafia.

'The Russian woman could have been a staff (agent of) Western intelligence staff.'

Altintas' sister Seher Ozeroglu, believed to be in her late 20s, is reported to have said it was as if her younger brother 'was guided by someone' when he killed the ambassador.

She implied this was a shadowy man known only as 'S' who her brother met in Ankara after he left the family's provincial home.

The alleged Russian woman - whose name, age and picture have not been revealed so far - is reported to be undergoing questioning by Vladimir Putin's security services.

Altintas's sister Seher Ozeroglu,pictured, is reported to have said it was as if her younger brother 'was guided by someone' when he killed the ambassador

According to Turkish newspaper Hurriyet Today, she left Ankara long before the assassination and travelled to Moscow, where she admitted they had a relationship.

There has been no direct comment from the Kremlin, which is working with the Turkish authorities in a major investigation to understand the motives behind the death of the 62-year-old diplomat.

The newspaper also claimed she could be a Western intelligence plant, or an alleged terrorist working for a grouping called FETO which is seen as opposing Turkish president Tayyip Recep Erdogan, or have links to the mafia.

There were also claims that the 'relationship' was based on payments from the assassin to the woman, but the report also suggested Altintas could have been coaxed towards becoming a killer, knowing he would die for what he did.

Turkish media claimed the woman involved with Altintas could be a Western intelligence plant, or an alleged terrorist working for a grouping called FETO. Pictured is the Turkish policeman moments after he shot the ambassador

A Turkish report which has been seized on by Russian media said: 'It is very important to understand who the woman is: from intelligence, FETO or mafia.

'The Russian woman could have been a staff (agent of) Western intelligence staff.

'Using her sexuality she might have established a relationship with a Turkish assassin who could have directed him towards suicide.'

Yet no evidence has so far been given that this was the case.

Russia has sent an 18-strong group of representatives from the Foreign Ministry, secret services and Investigative Committee, equivalent of the FBI, to Ankara to investigate the murder.

Andrey Karlov, pictured left, just moments before he was shot dead, right, at the art gallery in Ankara by Altintas

A key question is whether - as the Turkish authorities have claimed - he is linked to so-called FETO and supporters of Islamic cleric Fethullah Gulen who is accused of having orchestrated a coup that was suppressed by the Turkish authorities in July.

Altintas moved out of his flat and into a luxury hotel before gunning down the ambassador. Hotel Best is a 4-star hotel located on Ataturk Boulevard in Cankaya district of Ankara.

The 48-room hotel is described as being 'in the heart of Ankara' and all guest bedrooms 'are equipped with a private balcony, providing far-reaching views' across the city.

The killer shaved and dressed in a suit and tie before walking 150 metres to the art centre where he used his police ID to enter the premises.

A metal detector alarm went off because of his firearm, but he was waved through because of his assumed police status.