After Rosberg finished second at Sunday's Belgian Grand Prix, Hamilton claimed the German driver acknowledged that he had deliberately crashed into him early in the incident-packed race, which saw Daniel Ricciardo clinch his third win of the season.
"We just had a meeting about it and he basically said he did it on purpose," Hamilton said, struggling to contain his anger. "He said he did it on purpose. He said he could have avoided it. He said 'I did it to prove a point.'"
There was no immediate response from Rosberg, who now has 220 points with Hamilton still on 191 and third-placed Ricciardo on 156.
The huge tensions inside Mercedes overshadowed Ricciardo's impressive performance for resurgent Red Bull.
Rosberg effectively ended Hamilton's chances of victory on the second lap after a risky overtaking move that saw him clip and puncture the Briton's left tire.
Both of their cars were damaged, but not as much as their relationship.
"I heard someone say that it was inevitable we were going to crash one day, but I don't feel that today was that inevitability," Hamilton said. "It's not your job to go massively out of your way to leave extra, extra room."
Red Bull took full advantage as Ricciardo raced away to a second consecutive victory, beating Rosberg by 3.3 seconds. Hamilton retired five laps from the end as he slipped 29 points behind Rosberg overall.
Ricciardo's efforts were totally overshadowed by the third major Mercedes feud this season between Hamilton and Rosberg.
The two men's friendship — cemented in their junior days racing karts against each other — now appears in freefall.
"It's damaging this weekend for me, I don't know how I'm going to get back 30 points," Hamilton said, before aiming a thinly-veiled swipe at Rosberg ahead of the Italian GP in two weeks' time.
"We'll have to make sure we're not wheel to wheel (in Monza)," he said, stern-faced.
Both drivers spoke shortly after a team meeting, with Rosberg visibly shaken as he tried to downplay the incident.
"The stewards judged it's a racing incident. That's the best way to describe that," he said. "I didn't see any risk in trying to overtake so why should I not try? Inside was not possible so I tried round the outside. The opportunity was there."
Rosberg refused to reveal what was said at the team meeting.
"That wouldn't be the right thing to do," he said. "I don't want to go into details as to who apologized."
But an incredulous-sounding Hamilton maintained that Rosberg acknowledged he had deliberately nudged into Hamilton.
"I was gob-smacked when I was listening to the meeting. You need to ask him what point he was trying to make," Hamilton said. "He just came in there and said 'It was all my fault.' Just came in there ..."
Finnish driver Valtteri Bottas was third — although his fourth podium in five races went largely unheralded as Rosberg was jeered by the Spa crowd on the podium.
Even Mercedes executive director Toto Wolff blamed Rosberg.
"You don't try to overtake with the knife between your teeth in lap number two and damage both cars," he told BBC sport.
Ricciardo's beaming, toothy smile was in stark contrast to the glum mood at Mercedes.
The Australian continues to outshine his Red Bull teammate Sebastian Vettel, who finished fifth behind Ferrari's Kimi Raikkonen.
"To have three wins in 12 races has exceeded a few expectations. The in-team battle has gone really well," said Ricciardo, who is 35 points behind Hamilton. "I've shown speed throughout qualifying and in the race now."
Rosberg started from pole for the fourth straight race, but Hamilton and Vettel got past the German on turn 1.
As Hamilton fixed his racing line, Rosberg surged past on lap two and his front wing hit Hamilton's left side, also damaging Rosberg's car.
"Nico hit me, Nico hit me," an exasperated Hamilton shouted over the race radio.
Not again, the Mercedes team must have been thinking.
At last month's Hungarian GP, Hamilton refused team orders to let Rosberg past.
At the Monaco GP in May, Hamilton was incensed when Rosberg crashed late in qualifying when under no pressure, leading to a safety car coming out and squandering Hamilton's chances of securing pole position.
Hamilton felt confident after qualifying on the front row for the first time in six races.
But once again the 2008 champion needed to carve his way back through the field, just like in the previous two GPS — Hungary and Germany — where he qualified 20th and 22nd due to technical problems.
Rosberg's front wing was replaced on lap nine. Then, in a bizarre turn, some flying debris got attached to the radio aerial on the front of the car and flapped around in front of his face. He tried in vain to remove it after at one stage the string-like material even caught on the steering wheel.
"It eventually came off," he said. "I couldn't even see where I was going sometimes."