Toto Wolff has defended the Mercedes team’s recent dominance in Formula One as fulfilling his commitment to Mercedes and its personnel. The executive director insisted the team’s decision, criticised recently by Bernie Ecclestone, not to supply their rivals Red Bull with engines in 2015 had been correct. He sympathised with fans who wanted to see greater competition but stressed that his role was to look to the fortunes of Mercedes first.

Wolff was speaking on day two of the first test in Barcelona, where Mercedes are preparing to defend the drivers’ and constructors’ titles they have won for the past four seasons. Should they do so they will equal Ferrari’s record of taking the double five consecutive times, achieved with Michael Schumacher between 2000 and 2004.

Since the turbo hybrid era began in 2014 Mercedes have been in a class of their own, with only Ferrari able to match them last season under the new regulations. Their win rate has been extraordinary, with 16 victories from 19 races in 2014 and 19 from 21 in 2016.

Last week F1’s former executive Ecclestone held Wolff responsible for the dearth of close racing. “I blame Mercedes and Toto for putting us in the shit we are in terms of the competition,” he said. “If they’d given an engine to Red Bull, we’d have three teams for the past three years racing each other.”

Wolff responded at the Circuit de Catalunya, where Mercedes completed another solid day of testing with Valtteri Bottas driving 94 laps in second on the time sheets to Ferrari’s Sebastian Vettel. “I can see from a fan’s perspective that the more competitive teams there are the better it is, the more enjoyable it is,” Wolff said. “But it is not the task I have been given.

“I need to look to the best interests of this group of people – as much as I love hard racing and tough fights and the drama and the glory. Bernie said many times that if he had been in my position he would have made the same decision on the Red Bull engine.”

He did, however, accede to the evaluation that greater competition was in the sport’s best interests, as McLaren’s executive director Zak Brown has argued. “Zak and his people have a tough challenge to manage,” Wolff said. “McLaren is a mega brand and one of the iconic names in F1 but not successful in recent years. Reinstating that is a very difficult task and clearly Zak needs to use all available tools to make his team progress through the grid. So I accept the criticism.”

With track time limited because of the very low temperatures, Mercedes opted not use Lewis Hamilton in his scheduled afternoon session, instead keeping his team-mate Bottas in the car for the entire day.

New regulations, including engine rules, are being formulated and set to be implemented in 2021. Claire Williams, the Williams deputy team principal, stressed that the sooner the sport’s direction was clarified the better. “I think we have to get the engine regulations done, put them to bed and worry about other things,” she said. “We have bigger things to focus on, such as making this sport healthier as a whole rather than one element of it.”

Williams, who were fifth last season and are still an independent team with no manufacturer backing, are unable to compete in budget terms with Mercedes, Ferrari and Red Bull and believe the F1 owner, Liberty Media, must address the matter. “We are fully supportive of a cost cap and budget control in F1,” Williams said. “Spending £300m a year just to get two race cars to the grid is a scary amount of money and it’s not sustainable for our future. I think the fans of our sport want to see a much more competitive grid and that can only be the outcome of a more financially balanced sport.”