British GP: Lewis Hamilton & Nico Rosberg threatened with punishments by Mercedes

Mercedes drivers Lewis Hamilton and Nico Rosberg remain free to race but have been warned they can be punished if they crash together again.

The team said in a statement they had "strengthened our rules of engagement to include much greater deterrents to contact between our cars".

It comes after the two collided while disputing the lead on the last lap of Sunday's Austrian Grand Prix.

Mercedes said team orders could be imposed "as a solution of last resort".

But the imposition of team orders, which dictate that the drivers must hold position at a certain point in the race, would only come if the drivers "did not honour the revised rules of engagement".

The title rivals were given the ultimatum in meetings with team boss Toto Wolff at the Mercedes F1 factory on Thursday.

Rosberg was penalised for the incident by race stewards, who said he had not given Hamilton "racing room" as the Briton tried to overtake the German around the outside of Turn Two at the Red Bull Ring. Rosberg limped to the finish in fourth place with a damaged car.

Wolff, who called the collision "brainless", is determined it should not happen again.

The incident was their second crash in five races, after they took each other out on the first lap of the Spanish Grand Prix in May. They also banged wheels at the start of the Canadian Grand Prix, where both continued without damaged.Wolff contemplated "all options" in the days following Sunday's crash but, after meeting with senior management, decided not to impose team orders on the drivers.

The drivers have been told their freedom to race "came with duty to respect the values of the team".

After the Austria collision, Hamilton said he would "pray and hope" that Mercedes did not introduce team orders because it "robs" fans and "takes the joy" out of racing.

What does this mean?

Mercedes have not yet specified the exact form of any punishments the drivers could receive if they crash again.

However, the only penalties the team could impose that would have any significant deterrent effect would be a fine or suspension from a race.

Hamilton earns a reputed $31m (£23.9m) and Rosberg about half that so it can be assumed any fine would likely run into the millions, for it to have any deterrent effect.

In terms of sporting penalties, the only realistic serious threat the team has would be to exclude from a race the driver considered culpable.

The decision adds further spice to an already tense weekend at Silverstone, the 10th grand prix of a record 21-race season.

Hamilton trails Rosberg by 11 points following his Austria win, his third of the season. The German has taken five victories.