Toro Rosso will move a big step closer to Red Bull's premier Formula 1 team in 2017, boss Franz Tost has revealed.

Once regarded as effectively a 'satellite' team with a very similar car, Faenza-based Toro Rosso had to steer away from Red Bull Racing some years ago due to tighter customer car rules.

With the new American team Haas leaning heavily on Ferrari for parts this year, and Toro Rosso switching back from Ferrari to Renault power for 2017, Tost indicated that the second Red Bull team will change tack next year.

"The main reason we decided to go back to Renault is to use more synergies with Red Bull Technology," he explained in Montreal.

"We can get nearly the whole rear part from Red Bull Technology - the gearbox, hydraulics and also suspension systems, and this will help us make another step forward."

More uncertain for Toro Rosso heading into 2017 is the driver issue.

Next year would be a rare third in a row at Toro Rosso for Carlos Sainz, who has been linked with a move to a bigger team, while Daniil Kvyat has been making noises about wanting to leave the Red Bull family altogether.

When asked about drivers for 2017, team boss Tost answered: "I don't know yet.

"This is a decision that will be made by Red Bull at the end of the season. So far, I must say that Daniil has recovered very fast [after being dropped by Red Bull Racing] and I expect a very good second half of the season from him."

Toro Rosso sit fifth in the team standings ahead of the Canadian Grand Prix.