The previous two Azerbaijan Grand Prix have been dramatic affairs and the 2018 version was no different as Lewis Hamilton won an incident-packed race.
But the most controversial moment came on the 41st lap as Ricciardo attempted to pass Verstappen before the first corner but ran into the back of his team-mate ending the race for both of them.
After the race, Horner fumed at his drivers for costing the team points.
And he has now revealed that during a pre-race briefing, Ricciardo and Verstappen were told to avoid a replicating past crashes on the Baku circuit.
“We’ve discussed it at length on many, many occasions,” Horner said.
“We even discussed it in the morning, that we wanted to avoid a repeat of Force India’s scenario from last year, and that we would allow them to race, but please allow each other space.
“Unfortunately that hasn’t happened.
“Our drivers have been racing hard, on the limit, but in our mind fairly, but then unfortunately this incident has happened.
“We will discuss it prior to Barcelona, but we want to continue to allow the drivers to race.
“It was a racing accident, they’re both equally culpable, not one or the other more to blame.”