Miguel Oliveira couldn't hide his disappointment at KTM's decision to give rookie Brad Binder the vacant 2020 factory MotoGP seat.

Oliveira, doing an impressive job at the satellite Tech3 squad during his own debut premier-class season, was the obvious initial choice to take over following Johann Zarco's early exit from the official team.

KTM then seemed to be leaning towards handing the role to test rider Mika Kallio, who is finishing this season in place of Zarco.

But in a surprise twist, Binder - due to be Oliveira's Tech3 team-mate - will now go straight to the factory MotoGP team alongside Pol Espargaro next year.

It's a decision that has left Oliveira clearly disgruntled, despite KTM's Mike Leitner saying Oliveira turned the factory ride down.

The Portuguese explained he had been prepared to remain at Tech3 for a further season if the factory wanted the vast experience of Mika Kallio, but can't understand why Binder is a better choice than him.

"KTM approached me during the Misano GP and, they weren't really asking me anything or giving me the option, they just said that there was this seat that was available in the factory team and they were thinking about putting Mika there," Oliveira said on Thursday at Phillip Island.

"And I said, well if it's Mika [getting the ride] I think it's completely fine for me, because I had built a good relationship with the [Tech3] team and I think it doesn't make sense to make the switch.

"In any case, you know we were supposed to have a factory bike this year that didn't happen until recently and who knows about next year?

"This is the thing I want to look at, the KTM relationship in the long term and having chosen a rookie and a guy [Binder] who is the same age as me makes me feel a bit like I'm not worthy enough to be there.

"But it's their decision and I respect it. And it doesn't change any single thing on my mind of being here and doing the maximum."

Oliveira, who found out KTM's plans last Friday at Motegi, added that being in the official team not only means getting the latest-spec machinery but having a guiding hand in development of the RC16.

"The thing is, when you are offered the factory seat there are many other things at stake, like first of all you are guaranteed that you have a factory bike," said Oliveira.

"Secondly, you are more involved in the development of the parts and you get to try many things, which for me as a one-year experience MotoGP rider made more sense to be there [than Binder].

"But it doesn't make sense to them and this is the thing where we disagree. But again I respect that. There's nothing I can do."

Another area where Oliveira seemed unimpressed was the decision to put another rookie, Iker Lecuona, in place of Binder as Oliveira's new Tech3 team-mate.

"I think it was a rush move. Basically he's for sure a fast rider in Moto2, he has shown it a couple of times. But you know it was something that I think was forced," Oliveira said.

"It was never the ideal plan for KTM and for the whole project. But it's something that was made to do and maybe it will be a positive surprise next year and he can maybe also be fast on a KTM. We'll see."

Oliveira is 16th in the world championship, as the second-best KTM rider after Espargaro, with a best race finish of eighth place.