"We are not rushing into a decision," team boss Cyril Abiteboul said.
"The drivers we choose for will be the first drivers that we really choose as Renault, it is likely they will be here for a couple of seasons so I think we are not taking that decision lightly," he added.
Magnussen has expressed some frustration that, like in 2014 when he ultimately lost his place at McLaren, the decision is delayed.
His advisor Jesper Carlsen told BT newspaper: "The focus is of course on Renault, but it's important to keep options open.
"There might be openings at other teams, and if Kevin can continue to perform as he did (in Singapore) on Sunday, his position will of course be stronger and stronger."
As for Magnussen's frustration at the delay, Carlsen answered: "It's just the way it is and we must accept it.
"Kevin has just been told that he must focus on driving the car and getting as good results as possible. And on Sunday he really did that."
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