Alonso says Renault have got a big decision to make in the next few weeks

Double world champion Fernando Alonso thinks Renault should consider abandoning this season to concentrate on building a competitive car for 2009.

Alonso says the success of developments planned for the next two races in France and Britain should determine how his team approach the rest of the year.

"It's a difficult decision, and I have a strong opinion about it," he said.

"But after Silverstone [on 6 July] you have to think about it. The decision has to be made sooner or later."

The 26-year-old Spaniard's comments come after Renault's most competitive showing of the season.

Alonso was contesting second place in the Canadian Grand Prix with BMW Sauber driver Nick Heidfeld when he spun off on lap 45.

I think it is a miracle that a Renault is fighting against a BMW Fernando Alonso

But Alonso is under no illusions that Renault are still a considerable distance behind pace-setters McLaren and Ferrari, and even BMW Sauber.

"We have a couple of developments coming for Magny-Cours and Silverstone, so let's wait and see what these do to the car," Alonso said.

"Maybe at those tracks it will be good, so we can carry on developing this car.

"If it's not good, maybe the season will already be over so it's time to think about next year."

But he was optimistic the team could make a step forward for the French race on 22 June and Britain on 6 July.

Alonso spun out while contesting second place in Canada

"I'm sure we can go up in performance, and hopefully that will put us in the points for the championship."

Renault are only seventh in the constructors' standings after seven of 18 races this season.

Opportunities to score a big points haul have slipped through their fingers in the last two races following mistakes by Alonso.

Two weeks before the race in Canada, Alonso destroyed his chances in Monaco when an ill-advised passing attempt on Heidfeld led to a collision.

In his favour, though, the general perception is that Alonso's skill is lifting the team into places it would probably not otherwise be.

His team-mate, rookie Nelson Piquet Jr, has generally been nowhere near Alonso's pace.

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"I think it is a miracle that a Renault is fighting against a BMW," Alonso said after the Canadian race.

"I could have backed off, but I try to go at the limit and thus there is a bigger chance of making mistakes."

He said that in hindsight the team made a mistake calling him into the pits with the other front-runners when the safety car came out early in the race.

Had he stayed out, he said, he would have been ahead of both eventual winner Robert Kubica and his BMW team-mate Heidfeld.

"It was a big mistake and we would have won the race had it not occurred," Alonso said.

Instead, he found himself behind both at the back of a three-car battle for the lead and with a stop still to make after Heidfeld had made his sole visit to the pits.

The German quickly let Kubica through into the lead. Alonso was trying to pass Heidfeld when he spun.

"It is true I was third when I went off the track, but it was a tricky position because I had to stop again and I had cars behind that weren't going to stop," Alonso said.

"I was told over the radio that I would be eighth or ninth once I stopped for the second time. That would have meant being out of the points.

"So I had to try everything I could. I was trying to change my line to try to overtake Heidfeld and I got on to the dirty part and went off.

"I am not disappointed, these things can happen in the races and it is better they happen this year and not another."