Jenson Button has been given a kick up the backside by McLaren boss Ron Dennis ahead of this weekend's British Grand Prix.

With Button out of contract at the end of this season, the 34-year-old has been ordered to 'try harder' by Dennis.

McLaren Group CEO Dennis appreciates the car driven by both Button and team-mate Kevin Magnussen this season is far from a race winner.

Dennis, however, believes veteran Button should be leaving rookie Magnussen in his wake, with just 14 points separating the duo in the drivers' standings.

"I'm happy with the drivers in the sense I think they are giving their best," said Dennis, speaking to Sky Sports.

"I'm sure Kevin is giving a big wake-up call to Jenson. In some ways you say, 'Great, we've made a great choice with Kevin'.

"But in other ways you say, 'Come on Jenson, you are a world champion and absolutely one thing you can do on a consistent basis - and you should be doing it - is beating your team-mate'.

"Do I want him to try harder? Of course I do. He's a highly-paid grand prix driver.

"Yes, we are not giving him the best car; yes, it would be challenging for him to win in this car, to say the least, but he could do his bit and Kevin has to make it as difficult for him as possible."

Dennis has already made clear there will be no decision on the team's driver line-up for 2016 until later in the year.

That is presumably to assess the market as the year progresses and to see who, if anybody, becomes available.

"We want to win races and we would always hope the best available drivers would wish to drive our cars," added Dennis.

"The key word is 'available' because people have contracts and we respect those contracts.

"If Lewis (Hamilton) was in a position to drive for us next year, as with many of the other top drivers if they were in that position, we would love to have them on board.

"No-one should ever feel threatened, either as a driver or as an engineer. All we want to do is win and we have to take considered positions and considered decisions on that process."

Suggested to Dennis everyone is being kept on their toes, he replied: "Absolutely."