Fernando Alonso has signed a new contract at McLaren and Jenson Button believes he is the most complete driver on the Formula One grid.

Alonso ended speculation surrounding his immediate future on Thursday by agreeing a deal to remain at McLaren for 2018, when the team will operate with Renault power after cutting ties with Honda following three disappointing campaigns.

Button, who spent a pair of seasons as the Spaniard's team-mate, thinks the two-time world champion has everything you could desire in a driver.

Asked if Alonso's ability warranted more than the back-to-back titles he claimed in 2005 and 2006, Button, speaking at an event to promote his new book, told Omnisport: "I mean, who deserves what? You work hard for it but you've got to find yourself in the right place at the right time.

"Even if you're the best driver in the world and you're much better than everyone else it doesn't matter. If you don't have the equipment, you won't win.

"He's very talented. You can't judge someone's ability on how many world championships they won, I don't think.

"He's a world championship driver and he's probably the most complete driver on the grid, I would say."

Button filled in for Alonso at the Monaco Grand Prix when the 36-year-old took part in the Indy 500 in May, and the 2009 world champion expects his former team-mate to continue testing himself in other categories.

"I think he's like me. he's been in Formula One for many years, but he's a racing driver, not just an F1 driver, so you'll see him doing other things," he said.

"He did IndyCar, he did the Indy500 this year and I think next year he'll do other fun things as well."

Jenson Button's new book 'Life to the Limit: My Autobiography' from Blink Publishing is available now.