Fernando Alonso says he will stay at McLaren until 2017

Fernando Alonso is 16th in this year's drivers' championship with 11 points

Fernando Alonso has said he will see out the remaining two years of his McLaren contract after casting doubt on his future at the last race.

Asked after the Japanese Grand Prix whether he would be racing in Formula 1 next season, he said: "I don't know."

The remark came after radio messages in which he criticised his Honda engine.

At a news conference before the Russian Grand Prix, Alonso was asked whether he would be at McLaren next year and replied: "Yes. Of course. And 2017."

During last month's Japanese race, the two-time world champion likened the under-powered Honda turbo to an engine from the GP2 feeder category - where engines are around 300bhp down on the standard-setting F1 Mercedes engine.

The 34-year-old Spaniard said being passed on the straights by drivers from the midfield Sauber team was "very embarrassing".

On Thursday he said the criticisms had been due to "the frustration of battling hard and being a competitive sportsman in the car, racing hard and trying to give it all… fighting lap after lap and you keep being passed on the straight or before braking".

He added: "I'm happy it was just broadcast in Suzuka. If you heard all the radio messages over the year from me or Jenson (Button, his team-mate), you would be even more surprised."

But he said that, overall, he and Button had been very supportive of the team despite their uncompetitive performances this season.

"You talk on the radio and think it's private but we have been very, very positive," Alonso said.

"It's unique in our sport that we have microphones in helmets. Imagine that in the NBA or football."

Alonso added the "most important" aspect of the weekend in Japan had been a visit he made before the race to Honda's research and development facility.

"I saw the engine programme for next year," he said. "We talked about the difficulties we are facing right now and solutions for next year."

Fernando Alonso previously drove for McLaren in 2007 before rejoining the team this season

Alonso heads into this weekend's Russian race already knowing he will start from the back of the grid as a result of penalties for changing engine parts.

Honda have given him an upgraded internal combustion engine, designed using their remaining four in-season development tokens.

Because he has used more than the permitted five engines so far this season, that is a 10-place grid penalty in itself.

But Honda said it would also take the opportunity to change the engine's control electronics, turbo and the MGU-H, the electric motor that recovers energy from the turbo.

These will each mean an additional five-place penalty, adding up to a likely 25 places in total.

Honda said there had also been "a minor reliability update on the turbo".

Button will not be using the upgraded engine at this race as there is only one available.