The pair were just beginning their wheel-to-wheel battle for victory in Belgium when German Rosberg hit the sister Mercedes from behind.
Hamilton limped back to the pits with a shredded rear tyre but later retired altogether, blowing out his points deficit to almost 30 points.
Rowdy trackside fans instantly booed Rosberg, and their displeasure became even louder when the 29-year-old accepted his trophy for second place.
Their rudeness was rebuked by podium interviewer Eddie Jordan, and even Red Bull boss Christian Horner agreed that it was just a case of "two guys going for a world championship and the same piece of tarmac".
A sheepish Rosberg, not apologising, insisted: "I have not seen it on television yet so it wouldn't be good of me to comment.
"I will have a look at it and then speak about it."
Hamilton was predictably upset.
"I took the corner as I should because it was my line and I don't know why he hit me but I am sure he will leave here happy tonight," said the Briton, whose relationship with Rosberg had already hit rock bottom in the Monaco qualifying incident.
"I wouldn't say it was worse than Monaco because it couldn't get much worse than that," said Hamilton.
Notably, Mercedes chiefs Niki Lauda and Toto Wolff immediately backed Hamilton, pointing an unmistakable finger at Rosberg.
"Absolutely unacceptable," Wolff told British television BBC.
"We have often discussed the situation -- you don't try to overtake with the knife between your teeth in lap number two and damage both cars.
"This is a decisive moment in the battle between the two of them and for the team. Lewis is very upset," he added, "but he will recover quickly.
"It will be handled."
And if Rosberg was not immediately apologising, team chairman Niki Lauda did not hesitate: "Very simply sorry to Lewis.
"Very simply it is unacceptable that in the second lap Nico hit Lewis. Completely unacceptable.
"I thought they were clever enough to know that but obviously they aren't," said the great Austrian.
Hamilton, meanwhile, sounded doubtful he can recover from the latest blow to his 2014 hopes.
"If you notice, Rosberg's car rarely stops," he said. "It's looking good for him this season now.
"There's a lot of things going on in my mind. Maybe it just isn't my year but I can't let that overtake anything -- we have a great car and a great team and I will keep on fighting."
Hamilton also sounded unsure Wolff and Lauda's public rebuke of Rosberg will have any effect.
"It reminds me of when I was at school," he said, "the teachers will say something but they won't do anything. The stewards didn't do anything and I am now 30 points behind so I am just going to have push like hell."