Red Bull team chief Christian Horner on Friday defended Formula One's decision to postpone the introduction of cockpit "halos" and said not enough research and development had been carried out.

Horner spoke out after drivers' union boss Alex Wurz warned that the move, taken on Thursday by the F1 Strategy Group, had put business interests before driver safety.

"I disagree with that," said Horner. "We've agreed for a system to come in 2018, but it needs to be fully researched, developed and tested.

"At the moment, other than a couple of ­installation laps from a couple of drivers, there's been no [testing] mileage put on this."

He added that new tire compounds are always tested intensively and extensively before they are introduced and said the same rigor must be applied to safety components.

News of the rejection of the proposed cockpit protection device came just hours after four-time world champion Sebastian Vettel warned "­nothing justifies death."

The Ferrari driver said, "It would be the first time in human history that we've learned a lesson and we did not change."

The F1 Strategy Group made the decision at a meeting in Geneva where it also decided to make changes in other areas including a near-complete relaxation of restrictions on teams' radio communications and the introduction of wet race standing starts.

In a statement sent out on Friday morning, F1 Race Director Charlie Whiting said the lifting of radio restrictions was done to improve content for the fans and spectators.

His technical directive made clear that there would be no limits on the messages sent by teams except during the pre-race formation lap.

In another move, a proposal for a standing race start after a Safety Car period was agreed.