Vettel crashes into Button in Spa
Jenson Button blamed a "confused" Sebastian Vettel for the crash which took him out of the Belgian Grand Prix.
Vettel's Red Bull ran into Button on lap 16 as the defending world champion defended an overtaking manoeuvre, shunting his McLaren off the track.
"I defended my line about three inches on the inside and perhaps Sebastian got confused as to which direction to go," Button told BBC Sport's F1 Forum.
"I'm sorry, it was not my intention to destroy his race or mine," said Vettel.
The German was given a drive-through penalty for his error, and further incidents with Force India's Vitantonio Luizzi and Ferrari's Fernando Alonso contributed to him finishing only 15th after an incident-packed race.
Button frustrated by 'weird' move
For Button, however, his failure to score points left him trailing race winner and team-mate Lewis Hamilton by 35 points with only six races remaining in the calendar, an outcome he described as a "massive blow" to his chances of keeping his title.
The 30-year-old had taken advantage of pole-sitter Mark Webber's poor start to move into third place from fifth behind Hamilton and Robert Kubica, and he overtook the Pole's Renault to give McLaren a one-two at the head of the field.
However, Button sustained front wing damage in the 13th lap and had to cope with significant understeer, allowing Vettel to line him up for a series of overtaking moves.
But as he defended yet another attack going into the Bus Stop chicane, Vettel lost control of his RB6 and shoved into the side of Button's McLaren, forcing the Briton off the track.
"It was a strange incident and so sad because I was fighting for second position," said Button after the race.
"I thought I was doing a good job of defending with a damaged front wing, I just couldn't get enough front-end on the car especially through all of the right-handers through the back straight.
I was on the inside and it was clear I wasn't going to let him pass on the inside, but the outside was very clear for him.
"I'm guessing he [Vettel] thought I was going to pull from the left and he went on the inside. But he got a little rattled and didn't know which way to go.
"I thought I was doing a good job of keeping my position and fairly. It's a massive blow, I'm really disappointed."
Vettel conceded he was at fault for the accident with Button.
"I was faster than him, I knew it would be close," said Vettel, who trails Hamilton by 31 points in the drivers' standings.
"I tried to outbrake him on the outside but then I lost the braking and I couldn't control the car and crashed into him, ending my race and his.
Red Bull boss Christian Horner:
"The car wasn't perfect following the incident with Jenson, I had the penalty and looking back with the rain at the end, we could have managed to get decent points."
While ecstatic about Hamilton's first place on the podium, McLaren team principal Martin Whitmarsh said Vettel had denied his team a potential fourth one-two finish of the season.
"Without Sebastian's efforts we would be leading the constructors' championship," he told BBC Sport. "We've seen how good Jenson is in wet conditions and he was going to be competitive.
"To me, that [incident] has impacted on Jenson's championship and our team. A drive-through penalty seemed pretty light to me. The stewards will be busy reviewing a lot of things from this race so we shall see what happens."
Vettel's 15th-place finish left him third on 151 points in the drivers' standings, still four points ahead of Button.