Jenson Button (right) is yet to learn if he will continue to race alongside Fernando Alonso at McLaren

Jenson Button will have to wait until at least September to find out whether McLaren want to retain him alongside Fernando Alonso in 2017.

Chairman Ron Dennis says he will not consider whether to choose Button or reserve driver Stoffel Vandoorne until the Italian Grand Prix.

"We're not even talking about it until Monza," Dennis told BBC Sport. "Why should we decide now?"

Button, the 2009 world champion, is out of contract at the end of the season.

Dennis said there was no advantage in deciding now because, among other reasons, "you just disenchant a driver".

The team are believed likely to choose Belgian Vandoorne, who out-qualified the Briton and scored a point on his grand prix debut in Bahrain this year, where he was standing in for the injured Alonso.

But the decision could yet go in favour of Button, who has strong marketing appeal, vast experience and proven capability.

Alonso and Button are 14th and 15th respectively in the drivers' championship standings.

If McLaren did choose Button, they would likely try to retain a contractual relationship with Vandoorne and perhaps farm him out to another team to gain experience and better judge his potential.

Stoffel Vandoorne finished 10th in the Bahrain Grand Prix in April, his only F1 start to date

Dennis said in May that he considered the Belgian "an integral part of McLaren-Honda's future", adding: "Any team that imagines they may be able to poach him is very much mistaken. You may rest assured Stoffel is not for sale."

Vandoorne, who is considered the hottest prospect not yet in a full Formula 1 seat, is of interest to Renault, whose team principal Frederic Vasseur rates the 24-year-old extremely highly having run him in the GP2 feeder series, of which he is the reigning champion.

But Vandoorne cannot sign for another team until an option date in his McLaren contract lapses in the autumn.

Button is also of interest to Williams, who are likely to drop Brazilian Felipe Massa for next season.

Button's manager Richard Goddard said the 36-year-old had not yet decided what he wanted to do next season.

Williams have an option on Finn Valtteri Bottas and are likely to retain him, but have made no final decision on their driver line-up.

Alonso is under contract to McLaren until the end of 2017 and has said he will not make a decision on his future beyond that until he has experienced the new cars and Pirelli tyres that are being introduced next season.

These are aimed at making the cars a greater challenge to drive with the tyres able to withstand being driven much harder for a longer period than the current design, which have to be managed extensively.

The two-time champion told BBC Sport earlier this year that the tyres would be "a big factor" in his decision but added that if he stays in F1 into 2018 it will be with McLaren.