Daniel Ricciardo’s future at Red Bull is becoming untenable after a dramatic collision with teammate Max Verstappen ended both their races at the Azerbaijan Grand Prix.

Ricciardo smashed into the back of a swerving Verstappen in the latest instalment of their ugly rivalry, prompting a furious response from the Red Bull team.

They have clashed before, but this incident comes as Ricciardo is publicly considering a move to Ferrari or Mercedes for next season.

Race stewards ruled that Verstappen had moved twice to defend his position – when only one move is allowed – and said Ricciardo admitted he left it “too late” to overtake.

But according to Red Bull’s team principal Christian Horner, who was visibly unimpressed by the result, both drivers were at fault.

“They both recognise that they screwed up today and will be apologising to all the members of the team,” he told BBC after the race.

The pivotal moment in Baku 💥

Ricciardo and Verstappen collide in dramatic fashion

Recording a second double-DNF for Red Bull in three races#AzerbaijanGP 🇦🇿 #F1 pic.twitter.com/OMwH9Ct9BV

— Formula 1 (@F1) April 29, 2018

“There were probably three incidents between them through the race. They touched wheels and were told to calm it down, we don’t want to interfere with them going wheel-to-wheel. We are not apportioning blame one way or the other, they are both to blame for this.

“Our intention is to continue to let them race but they have to show respect and give space. They have been reminded that they are part of a team, they are highly paid individuals with the team’s interest at heart. The message was delivered very clearly.

“They are both in the doghouse.”

Both drivers received a formal reprimand, and each apologised to Red Bull.

“This is the last thing we wanted. We want to be able to race and I’m thankful that the team let us race,” Ricciardo said.

“Everyone is pretty heartbroken.”

Daniel Ricciardo walks off the track after retiring from the Azerbaijan Grand Prix. Photo: AAP

Verstappen said he didn’t want the team to stop him fighting Ricciardo on the track in the future.

“We will learn from this and have to make sure it doesn’t happen again,” Verstappen said.

The incident echoes an earlier generation of Red Bull rivalry.

The relationship between the team’s two star drivers of the early 2010s, Sebastian Vettel and Australia’s Mark Webber, turned increasingly toxic during their five seasons together, especially after they collided while fighting for the lead in Turkey in 2010.

In later years, the team limited how much Vettel and Webber could compete, sometimes imposing team orders for one driver to let the other through.

Verstappen has been under the microscope this season for his aggressive racing style.

To his fans, he adds spirit to a sport which can sometimes seem sterile; to his critics he’s downright dangerous.

At the last race in China, he hit Vettel’s Ferrari, dropping the German to eighth.

Ricciardo publicly criticised Verstappen at last year’s race in Hungary after Verstappen swerved into him trying to overtake and knocked Ricciardo out of the race.

Unusually for him, Verstappen subsequently apologised.

After being on the receiving end of reckless driving at the Singapore GP last September, Vertappen was quick to blame Sebastian Vettel after the German driver caused a first-turn crash that put both of them out.

He also had heated verbal clashes with Vettel and Kimi Raikkonen during the 2016 season.

-With AAP