Red Bull's Helmut Marko has defended the energy drink's arguably failed junior driver development programmes.

With Toro Rosso's Red Bull-developed lineup of Scott Speed and Vitantonio Liuzzi on the verge of collapse, former grand prix racer Marko - whose role at races is to liaise with Red Bull's drivers - insisted that the company's up and coming stars justify the driver programme.

"We have some very good people (on the programme)," the Austrian said in an interview with motorline.cc.

"One of them is Sebastien Buemi, who is in F3 and recently did a very good formula one test."

Marko also singled out Brendon Hartley and Filipe Albuquerque as young stars of the future.

"So we have a multiplicity of good drivers who are very successful in the junior categories," he insisted.

"If you make your judgement about Red Bull's junior programme only on the basis of the performance of Speed and Liuzzi, then I don't think that is fair."

Source: GMM