A British oil executive - named by Sky News sources as Nicholas Mockford - has been shot dead in Brussels.

The killing took place on October 14 but Belgian investigators have only just revealed information about his death.

Mr Mockford, who worked for ExxonMobil, was killed as he left a restaurant with his wife.

The Foreign Office said: "We can confirm the death of a British national in Brussels on October 14 and we are providing consular assistance."

Police said the businessman was shot as he left an Italian restaurant in Neder-Over-Heembeek, a suburb of the Belgian capital.

It happened at around 10pm as he walked with his wife Mary from the Da Marcello restaurant on Rue de Beyseghem to their car, which was parked nearby.

Mrs Mockford was violently attacked and struck several times on her face, as one of the attackers tried to grab her handbag.

A second attacker opened fire on the 60-year-old oil executive, who later died of his injuries.

He was shot three times, once as he lay on the floor, and his wife Mary was left beaten and covered in blood, cradling her husband and shouting for help. He died on the way to hospital.

Witnesses say they saw the couple walk across the street to their Lexus 4x4 car before shots were fired.

It is understood the two men were carrying motorcycle helmets and they initially fled on foot before taking a ring road on a "two-wheeled vehicle".

Shortly after the events, a white van passed Rue de Beyseghem and came across the victims.

Investigators have been questioning the driver of this vehicle.

A neighbour, who does not want to be identified, rushed out to the scene and said: "I heard a strange sound like, tak, tak. I thought that was strange, so I went out to have a look.

"And there was someone lying on the footpath on the other side of the street and someone saying, 'Au secours, au secours (Help, help).' There was someone lying unconscious next to a car."

The neighbour first thought the husband had been in a hit-and-run: "I stayed with them. At one point, he stopped breathing and I gave him first aid and he came back round.

"Then he was again unconscious and I again gave him first aid and brought him round, then the ambulance arrived."

The neighbour then understood that the man had been shot.

She said: "I saw when the ambulance arrived and cut open his shirt and that he had a bullet in his chest and blood on his head. But, of course, I didn’t want to move him."

The Daily Telegraph said police in Belgium were considering all possible motives for the shooting, including a carjacking, although Mr Mockford's car was not stolen.

Chief Inspector Wim Van Leifferenge said no-one had been arrested and those responsible were still on the run.

Mr Mockford is understood to have worked for ExxonMobil since the 1970s and was head of marketing for interim technologies for ExxonMobil Chemicals, Europe, promoting new types of greener fuel.

Brought up in Leicestershire, he had moved abroad from Chichester some years ago, living in Belgium and Singapore.

He was married to his Belgian wife for 15 years and had three grown-up children living in Britain from his first marriage, according to the Telegraph.

A family member, who asked not to be named, told the newspaper they thought he had been killed in a professional hit.

The relation said: "We are all confused about what has happened. Nick was a genuinely lovely, clean-cut, mild-mannered, family man."

He added: "He was shot so calmly and so quickly, it smacks horribly of a professional hit, but we can't fathom why. He isn't the type to cave in to blackmail and it just doesn't compute."

A spokesman for ExxonMobil said: "Mr Mockford, a British national, was a department manager at our office close to Brussels, but we have no indication that the incident was work related.

"Our thoughts are with his family, friends and colleagues and we are supporting them as best we can at this very difficult time."