Mercedes motorsport boss Toto Wolff has warned feuding drivers Lewis Hamilton and Nico Rosberg he will act should they step out of line in future.

As the championship battle has intensified between the duo over the past few weeks, so their relationship has disintegrated.

It has resulted in each taking measures deemed to be unacceptable by the other, to such an extent Press Association Sport understands they are no longer on speaking terms.

Certainly that was the case following the Monaco Grand Prix, won by Rosberg from lights-to-flag, with Hamilton runner-up to end his run of four successive wins and to fall four points behind the German in the drivers' standings.

It was the culmination of a contentious weekend in the principality, with Hamilton believing Rosberg acted deliberately with a manoeuvre in qualifying that yielded yellow flags and denied the Briton a shot at pole position.

Two weeks earlier in Barcelona, however, Hamilton had turned up the wick on his power unit to keep Rosberg at bay over the dying stages of the Spanish Grand Prix, in contravention of a direct, behind-the-scenes team order not to.

That was as a consequence of Rosberg doing the same in Bahrain as he hunted down Hamilton, only to fall short in his quest.

With the situation becoming tit-for-tat, Wolff said: "I can tell you, on the Sunday in Barcelona we had some emotions from the other side (Rosberg), which is understandable.

"You are in the car, alone out there, you don't have a perspective of what is going on around you.

"Obviously if you lose out to your team-mate, either in qualifying or in the race, that is a frustrating situation.

"In Barcelona, Nico felt aggrieved by what had happened in the race and I guess this is really normal.

"Everybody has their own absolute reality, absolute belief. I guess it is like arguing with somebody where you think you are right, the other person thinks he is right, but it is never black and white. There is sometimes grey.

"Right now I think they are probably exploring how far you can step over the line and what the consequences are. Isn't that normal?

"You have a chance of winning the championship, and as long as it isn't detrimental to the team spirit, as long as it is not underhand, we will handle the situation in the way we did before.

"But the moment it goes in the direction where we believe it is not in the spirit of Mercedes-Benz we will act accordingly.

"For instance, what happened with the engine settings, that is never going to happen again."

For now, Wolff can understand the emotions of his drivers, adding: "When you have a car capable of winning a race, a championship, there is fighting whenever you can fight.

"There is always some intensity and emotions in whatever you do, and that is normal."