Red Bull is not happy with its second formula one team, Toro Rosso.

That is the admission of the energy drink company's key official Dr Helmut Marko, who is regarded as the closest motor racing confidante of Red Bull mogul Dietrich Mateschitz.

He said of Toro Rosso: "We bought the team because the regulations allowed the use of much the same chassis as another team. Then it was changed."

And he says the plan to develop Toro Rosso into a traditional F1 team has not quite worked out.

"A great investment was made in Toro Rosso," Marko told Brazil's Globo, "but they cannot materialise that into points.

"The drivers and the team make mistakes, as well as technical failures. The car, the package would be good enough for fifth, but they cannot do it," he insisted.

So when asked if Red Bull has thought about selling Toro Rosso, Marko answered: "I don't think it is the best time now because Liberty is talking about distributing money better so the smaller teams get more.

"That could turn out to be a good deal. But it's also true that at the moment the cost to Red Bull is very high," he added.

A more immediate issue for Toro Rosso is drivers, with Carlos Sainz coveted by Renault but under contract to Red Bull for 2018.

"Yes, we have been approached by them," Marko confirmed.

"Carlos has a contract with us. We will need to find a solution that satisfies us, as we invested heavily in his development."

Complicating the issue is that Renault is looking into getting Robert Kubica back up and running for 2018, but boss Cyril Abiteboul said at Spa that he is not sure the Pole is able to return.

"I believe we will have a clearer view of the outcome of this story at Monza," Marko said.

Another problem for Red Bull is that its driver programme appears to have stalled, even though Pierre Gasly is being linked with a Toro Rosso debut for 2018.

But apart from that, "There is no one at the moment", Marko admits.

"If you look at the other categories, apart from Leclerc there is no one. (Lando) Norris is very good but he also makes a lot of mistakes.

"What is really wrong is the number of categories," Marko said. "With less championships there would be a grid of 30, the level would rise a lot and we would see who is really good."

(GMM)