The Ferrari man responded by pulling up alongside Hamilton, gesticulating and then seemingly driving into the side of the Mercedes before falling back in line.

Hamilton denied braking suddenly and labelled his rival a "disgrace" - with Vettel hit with a 10-second stop-and-go penalty and handed three penalty points on his licence following his actions.

But, while Stewart feels Vettel has tarnished his reputation with the stunt, the Scot - world champion in 1969, 1971 and 1973 - reckons Hamilton should accept a portion of the responsibility for the flashpoint.

"His reputation is certainly tarnished," Stewart said when asked about Vettel's actions.

"But at the same time what created the incident is what occurred when Lewis slowed down so quickly in a very unlikely place. You have got to take that into account.

"That was a shock to Sebastian, and that is why he came alongside Lewis to ask 'what the hell are you doing?' What Vettel then did was to unquestionably collide with Hamilton. There is no room for that, no excuse for that and it is wrong. It is inappropriate behaviour.

"It would be very simple to put the complete blame on one man, but what initiated the bad behaviour was what happened before.

"It was totally unexpected. I am not trying to hook Lewis into this the wrong way, but that was the whole crux of what happened.

"Lewis put his brakes on so hard that Vettel hit him. I am not blaming Lewis for the accident but I have to say I have never seen anyone come off the throttle so quickly. You either to do it to surprise them, but what happened was the surprise was too severe."

The incident occurred at the end of a second safety car period during a frenetic race in Baku that was eventually won by Red Bull's Daniel Ricciardo.

There were three safety cars deployed as Hamilton was forced to pit for a repair to his headrest just as Vettel was hit with his time penalty.

That left the pair squabbling over fourth and fifth, with Vettel holding off Hamilton to finish behind Valtteri Bottas and Lance Stroll.

Stewart also questioned Formula One's current set-up for dealing with such occurrences.

The FIA, motorsport's governing body, currently has three to four race stewards per grand prix, with one former driver making up part of the panel.

They are rotated on a regular basis and most are drivers who ended their racing careers some years ago - with the likes of Nigel Mansell, Derek Warwick, Mark Blundell and Mika Salo having filled the role.

In Baku it was American Danny Sullivan who was the appointed former driver, having raced in 15 F1 races for Tyrrell in 1983.

Stewart wants to see a regular position for an ex-driver from an era closer resembling that of today's racing.

Asked if Vettel should face FIA sanctions, the 78-year-old said: "There is room for more disciplinary action, but I have criticism about the stewarding at races.

"There are a different set of stewards at almost every grand prix. In my opinion, the FIA should choose a retired grand prix driver, give him a proper salary, and a position that he is the authority.

"They should sign him to a two-to-three year programme so he has full knowledge of all the drivers' behaviour. It would take somebody that has been in the business recently, who has retired.

"At the moment we are dealing with a bunch of extremely mature representatives from countries who are signed up by the FIA. They swap these people around to give them an opportunity to come to a grand prix.

"That is servicing the FIA's good relationships with nations. Those so-called stewards could come from a variety of different places and many of them are of different ages.

"They can't then possibly give consistency to either the disciplinary actions or have the knowledge that is required to make judgements that could affect the outcome of world championships.

"(FIA president) Jean Todt won't like me saying this, but I don't think it is as professionally handled as it should be."

Hamilton and Vettel will renew their title fight in Austria in a fortnight's time, with the latter 14 points clear at the top of the drivers' championship.